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Exploring differential two-particle correlations in $γp$ and low-multiplicity pp collisions using PYTHIA8
Authors:
Subash Chandra Behera,
Dukhishyam Mallick
Abstract:
A study of two-particle differential number ($B$) and transverse momentum ($P_{2}^\mathrm{CD}$) balance functions in photon-proton ($γp$) and proton-proton (pp) collisions at $\sqrt{s}=$ 5.36 TeV is presented. The analysis focuses on inclusive charged hadrons within the pseudorapidity coverage $|η|<2.4$ and the transverse momentum interval $0.3 < p_\mathrm{T} < 3.0$ GeV and examines their correlat…
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A study of two-particle differential number ($B$) and transverse momentum ($P_{2}^\mathrm{CD}$) balance functions in photon-proton ($γp$) and proton-proton (pp) collisions at $\sqrt{s}=$ 5.36 TeV is presented. The analysis focuses on inclusive charged hadrons within the pseudorapidity coverage $|η|<2.4$ and the transverse momentum interval $0.3 < p_\mathrm{T} < 3.0$ GeV and examines their correlations in terms of relative pseudorapidity ($Δη$) and relative azimuthal angle ($Δφ$). The correlation functions are evaluated for same- and opposite-sign pairs, and their combinations are used to extract charge-dependent (CD) and charge-independent (CI) components. The evolution of the near-side peak of the CD correlations is investigated in terms of $Δη$ and $Δφ$ as a function of charged-particle multiplicity ($N_\mathrm{ch}$) for $γp$ collisions and compared to pp collisions at a similar multiplicity range. A clear multiplicity dependence of the balance function width is obtained. The width is found systematically lower in $γp$ events than in pp collisions. This study provides valuable information on particle correlations and production mechanisms in low-$N_\mathrm{ch}$ regimes for upcoming measurements in small systems.
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Submitted 23 February, 2026;
originally announced February 2026.
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Jet-associated Balance Functions of Charged and Identified Hadrons in pp Collisions at $\sqrt{s}=13.6$ TeV using PYTHIA8
Authors:
Subash Chandra Behera,
Arvind Khuntia
Abstract:
We present a study of charge balance functions inside jets in proton-proton collisions at $\sqrt{s}=13.6$ TeV using the PYTHIA8 event generator. The balance function is a differential observable of opposite-charge correlations, which is calculated in the jet frame for inclusive charged hadrons and the identified $π$, $K$, and $p$. The results show a clear narrowing of the balancing width with incr…
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We present a study of charge balance functions inside jets in proton-proton collisions at $\sqrt{s}=13.6$ TeV using the PYTHIA8 event generator. The balance function is a differential observable of opposite-charge correlations, which is calculated in the jet frame for inclusive charged hadrons and the identified $π$, $K$, and $p$. The results show a clear narrowing of the balancing width with increasing jet charged multiplicity, indicating that particle production becomes more localized in momentum space in high-multiplicity jets.This trend resembles features attributed to collective expansion in heavy-ion collisions. The species dependence highlights sensitivity to the redistribution of strangeness and baryon number during string fragmentation and color reconnection. The new CR tune yields a little broader proton balance-function width in $Δφ^{*}$ than CP5, hinting at enhanced baryon-production dynamics, whereas meson widths differ only mildly. These comparisons suggest that multiparton interactions and color reconnection contribute to the observed trends, potentially generating collective like features inside jets, especially in high multiplicity jets, via nontrivial color dynamics alongside standard fragmentation. Taken together, the results establish identified hadron balance functions in high multiplicity jets as a sensitive probe of hadronization and provide new constraints for models of small system collectivity.
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Submitted 3 February, 2026;
originally announced February 2026.
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Probing Late-Stage Hadronic Interactions at High Baryon Density via $K^{*0}$ Production in the RHIC Beam Energy Scan Program
Authors:
STAR Collaboration,
B. E. Aboona,
J. Adam,
G. Agakishiev,
I. Aggarwal,
M. M. Aggarwal,
Z. Ahammed,
A. Aitbayev,
I. Alekseev,
E. Alpatov,
A. K. Alshammri,
A. Aparin,
S. Aslam,
J. Atchison,
G. S. Averichev,
V. Bairathi,
X. Bao,
P. Barik,
K. Barish,
S. Behera,
P. Bhagat,
A. Bhasin,
S. Bhatta,
I. G. Bordyuzhin,
J. D. Brandenburg
, et al. (363 additional authors not shown)
Abstract:
A precision measurement of the $K^{*0}$ meson yield is reported in Au+Au collisions at $\sqrt{s_{NN}} = 7.7,\; 11.5,\; 14.6,\; 19.6,$ and $27~\mathrm{GeV}$ using the high-statistics data sample collected by the STAR experiment during the Beam Energy Scan II (BES-II) program at RHIC. The transeverse momentum ($p_{T}$)-integrated yield ratios $(K^{*0} + \overline{K^{*0}})/(K^{+} + K^{-})$ in central…
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A precision measurement of the $K^{*0}$ meson yield is reported in Au+Au collisions at $\sqrt{s_{NN}} = 7.7,\; 11.5,\; 14.6,\; 19.6,$ and $27~\mathrm{GeV}$ using the high-statistics data sample collected by the STAR experiment during the Beam Energy Scan II (BES-II) program at RHIC. The transeverse momentum ($p_{T}$)-integrated yield ratios $(K^{*0} + \overline{K^{*0}})/(K^{+} + K^{-})$ in central collisions show a suppression relative to peripheral collisions at the $(1.7\text{-}3.6)\,σ$ level, while a thermal model without final-stage rescattering overpredicts this ratio with a deviation of $(6.9\text{-}8.2)\,σ$. These results indicate a loss of the measured $K^{*0}$ signal in central collisions due to re-scattering of its hadronic decay products in the hadronic phase. The $p_{T}$-integrated yield of charged kaons exhibits an approximate scaling with charged-particle multiplicity, independent of collision energy and system size. A similar trend is observed for the short-lived $K^{*0}$ resonance, although significant deviations emerge at lower energies. At BES energies, the $K^{*0}/K$ ratio shows stronger suppression than at the highest RHIC and LHC energies within a given multiplicity bin, particularly in central and mid-central collisions. This behavior is consistent with changes in the effective hadronic interaction cross section and is supported by transport model calculations, which indicate dominant meson-baryon interactions at lower energies and meson-meson interactions at higher energies.
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Submitted 28 April, 2026; v1 submitted 21 January, 2026;
originally announced January 2026.
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Identified charged hadron production in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 54.4 GeV with the STAR detector
Authors:
STAR Collaboration,
B. E. Aboona,
J. Adam,
G. Agakishiev,
I. Aggarwal,
M. M. Aggarwal,
Z. Ahammed,
A. Aitbayev,
I. Alekseev,
E. Alpatov,
A. K. Alshammri,
A. Aparin,
S. Aslam,
J. Atchison,
G. S. Averichev,
V. Bairathi,
X. Bao,
P. Barik,
K. Barish,
S. Behera,
P. Bhagat,
A. Bhasin,
S. Bhatta,
I. G. Bordyuzhin,
J. D. Brandenburg
, et al. (363 additional authors not shown)
Abstract:
We present results on the production of $π^{\pm}$, $K^{\pm}$, $p$, and $\bar{p}$ in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 54.4~GeV using the STAR detector at RHIC, at midrapidity ($|y| <$ 0.1). Invariant yields of these particles as a function of transverse momentum are shown. We determine bulk properties such as integrated particle yields ($dN/dy$), mean transverse momentum (…
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We present results on the production of $π^{\pm}$, $K^{\pm}$, $p$, and $\bar{p}$ in Au+Au collisions at $\sqrt{s_\mathrm{NN}}$ = 54.4~GeV using the STAR detector at RHIC, at midrapidity ($|y| <$ 0.1). Invariant yields of these particles as a function of transverse momentum are shown. We determine bulk properties such as integrated particle yields ($dN/dy$), mean transverse momentum ($\langle p_{T} \rangle$), particle ratios, which provide insight into the particle production mechanisms. Additionally, the kinetic freezeout parameters ($T_\text{kin}$ and $\langle β_{T} \rangle$), which provide information about the dynamics of the system at the time of freezeout, are obtained. The Bjorken energy density ($ε_{\rm{BJ}}$), which gives an estimate of the energy density in the central rapidity region of the collision zone at the formation time $τ$, is calculated and presented as a function of multiplicity for various energies. The results are compared with those from the models such as A Multi-Phase Transport (AMPT) and Heavy Ion Jet INteraction Generator (HIJING) for further insights.
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Submitted 21 May, 2026; v1 submitted 6 December, 2025;
originally announced December 2025.
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Observation of charmonium sequential suppression in heavy-ion collisions at the Relativistic Heavy Ion Collider
Authors:
STAR Collaboration,
B. E. Aboona,
J. Adam,
L. Adamczyk,
I. Aggarwal,
M. M. Aggarwal,
Z. Ahammed,
A. K. Alshammri,
E. C. Aschenauer,
S. Aslam,
J. Atchison,
V. Bairathi,
X. Bao,
P. Barik,
K. Barish,
S. Behera,
R. Bellwied,
P. Bhagat,
A. Bhasin,
S. Bhatta,
S. R. Bhosale,
J. Bielcik,
J. Bielcikova,
J. D. Brandenburg,
C. Broodo
, et al. (372 additional authors not shown)
Abstract:
We report measurements of charmonium sequential suppression in Ru+Ru and Zr+Zr collisions at $\sqrt{s_{\mathrm {NN}}}$ = 200 GeV with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The inclusive yield ratio of $ψ$(2S) to J/$ψ$ as a function of transverse momentum is reported, along with the centrality dependence of the double ratio, defined as the $ψ$(2S) to J/$ψ$ ratio in heav…
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We report measurements of charmonium sequential suppression in Ru+Ru and Zr+Zr collisions at $\sqrt{s_{\mathrm {NN}}}$ = 200 GeV with the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The inclusive yield ratio of $ψ$(2S) to J/$ψ$ as a function of transverse momentum is reported, along with the centrality dependence of the double ratio, defined as the $ψ$(2S) to J/$ψ$ ratio in heavy-ion collisions relative to that in $p$+$p$ collisions. In the 0-80% centrality class, the double ratio is found to be 0.41 $\pm$ 0.10 (stat) $\pm$ 0.03 (syst) $\pm$ 0.02 (ref), lower than unity with a significance of 5.6 standard deviations. This provides experimental evidence that $ψ$(2S) is significantly more suppressed than J/$ψ$ in heavy-ion collisions at RHIC. This sequential suppression pattern seems to increase from peripheral to central collisions, but with no significant dependence on the transverse momentum.
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Submitted 9 March, 2026; v1 submitted 16 September, 2025;
originally announced September 2025.
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Study of the beyond standard model interaction using Coherent Elastic Neutrino-Nucleus Scattering process
Authors:
S. P. Behera,
S. Panda,
D. K. Mishra
Abstract:
We have conducted an extensive study that highlights the potential of the Indian Coherent Neutrino-nucleus Scattering Experiment (ICNSE) detector in constraining neutrino-quark interactions that go beyond the standard model. By utilizing reactors with varied core configurations and power outputs as sources for electron antineutrinos, and operating with a target mass of 10 kg over a year, our findi…
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We have conducted an extensive study that highlights the potential of the Indian Coherent Neutrino-nucleus Scattering Experiment (ICNSE) detector in constraining neutrino-quark interactions that go beyond the standard model. By utilizing reactors with varied core configurations and power outputs as sources for electron antineutrinos, and operating with a target mass of 10 kg over a year, our findings reveal that the ICNSE detector is remarkably effective in narrowing down the vast majority of the Non-standard Interaction (NSI) parameter space. Moreover, incorporating results from two distinct detectors, like sapphire and high-purity germanium, markedly enhances sensitivity by reducing the degeneracies between some pairs of NSI parameters to a smaller region.This research highlights its role in enabling future developments and investigations.
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Submitted 25 May, 2026; v1 submitted 17 June, 2025;
originally announced June 2025.
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Study of neutron response using time of flight technique in ISMRAN detector
Authors:
R. Dey,
P. K. Netrakanti,
D. K. Mishra,
S. P. Behera,
R. Sehgal,
V. Jha,
L. M. Pant
Abstract:
We report the measurements of the fast neutron energy response in Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) detector consisting of an array of 9$\times$10 Plastic Scintillator Bars (PSBs) at BARC, Mumbai. ISMRAN is an above ground detector setup at $\sim$13 m from the Dhruva reactor core for the detection of reactor anti-neutrinos (${\overline{\ensuremathν}}_{e}$) via the inve…
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We report the measurements of the fast neutron energy response in Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) detector consisting of an array of 9$\times$10 Plastic Scintillator Bars (PSBs) at BARC, Mumbai. ISMRAN is an above ground detector setup at $\sim$13 m from the Dhruva reactor core for the detection of reactor anti-neutrinos (${\overline{\ensuremathν}}_{e}$) via the inverse beta decay (IBD) process. The dominant sources of reactor-related background in the vicinity of the detector are high energy $γ$-rays and fast neutrons. Therefore, a good understanding of fast neutron response in PSB is an essential pre-requisite for suppression and discrimination of the fast neutron background from IBD events. Kinetic energies of the fast neutron were determined using the Time-of-Flight (TOF) technique, which is used to get the scintillation light yield due to recoiling proton in PSB. We also measured the fast neutron capture time distribution in ISMRAN array using a novel technique involving TOF of the measured fast neutrons. The observed characteristic neutron capture time ( $τ$ ) of 68.29 $\pm$ 9.48 $μ$s is in good agreement with GEANT4 based MC simulation. These experimentally measured results will be useful for discriminating correlated and uncorrelated (accidental) background events from the true IBD events in reactor ON and OFF conditions inside the reactor hall.
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Submitted 15 June, 2025;
originally announced June 2025.
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Discrimination of neutron-$γ$ in the low energy regime using machine learning for an EJ-276D plastic scintillator
Authors:
S. Panda,
P. K. Netrakanti,
S. P. Behera,
R. R. Sahu,
K. Kumar,
R. Sehgal,
D. K. Mishra,
V. Jha
Abstract:
In this work, we present results for discrimination of neutron and $γ$ events using a plastic scintillator detector with pulse shape discrimination capabilities. Machine learning (ML) algorithms are used to improve the discriminatory power between neutron and $γ$ events at lower energy ranges which otherwise are not addressed by the conventional pulse shape discrimination techniques. The use of a…
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In this work, we present results for discrimination of neutron and $γ$ events using a plastic scintillator detector with pulse shape discrimination capabilities. Machine learning (ML) algorithms are used to improve the discriminatory power between neutron and $γ$ events at lower energy ranges which otherwise are not addressed by the conventional pulse shape discrimination techniques. The use of a multilayer perceptron with Bayesian inference (MLPBNN) and support vector machine (SVM) algorithms are studied using the recorded waveforms from the detector. Input variables are constructed for the ML algorithms, which captures the essence of the differences in the head and tail part of the neutron and $γ$ waveforms. A new variable, which utilizes the product of kurtosis and variance calculated from the waveform gives better ranking in terms of separation of neutron and $γ$ events. The training and the testing of the ML algorithms are done using an AmBe neutron source. In the lower energy region, the results obtained from the ML predictions are compared with the results obtained from a time of flight (ToF) technique to benchmark the overall performance of the ML algorithms. A reasonable agreement is observed between the results obtained from ML algorithm and the ToF experiment in the studied energy range. The MLPBNN gives better discriminatory power for the neutron and $γ$ events than the SVM algorithm.
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Submitted 18 November, 2025; v1 submitted 13 June, 2025;
originally announced June 2025.
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Onset of Constituent Quark Number Scaling in Heavy-Ion Collisions at RHIC
Authors:
STAR Collaboration,
B. E. Aboona,
J. Adam,
L. Adamczyk,
I. Aggarwal,
M. M. Aggarwal,
Z. Ahammed,
A. K. Alshammri,
E. C. Aschenauer,
S. Aslam,
J. Atchison,
V. Bairathi,
X. Bao,
K. Barish,
S. Behera,
R. Bellwied,
P. Bhagat,
A. Bhasin,
S. Bhatta,
S. R. Bhosale,
J. Bielcik,
J. Bielcikova,
J. D. Brandenburg,
C. Broodo,
X. Z. Cai
, et al. (347 additional authors not shown)
Abstract:
Partonic collectivity is one of the necessary signatures for the formation of quark-gluon plasma in high-energy nuclear collisions. Number of constituent quarks (NCQ) scaling has been observed for hadron elliptic flow $v_2$ in top energy nuclear collisions at the Relativistic Heavy Ion Collider and the LHC, and this has been theoretically suggested as strong evidence for partonic collectivity. In…
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Partonic collectivity is one of the necessary signatures for the formation of quark-gluon plasma in high-energy nuclear collisions. Number of constituent quarks (NCQ) scaling has been observed for hadron elliptic flow $v_2$ in top energy nuclear collisions at the Relativistic Heavy Ion Collider and the LHC, and this has been theoretically suggested as strong evidence for partonic collectivity. In this Letter, a systematic analysis of $v_2$ of $π^{\pm}$, $K^{\pm}$, $K^{0}_{S}$, $p$, and $Λ$ in Au+Au collisions at ${\sqrt{s_{_{\rm{NN}}}}}$ = 3.2, 3.5, 3.9, and 4.5 GeV, with the STAR experiment at the Relativistic Heavy Ion Collider, is presented. NCQ scaling is markedly violated at 3.2 GeV, consistent with a hadronic-interaction dominated equation of state. However, as the collision energy increases, a gradual evolution to NCQ scaling is observed. This beam-energy dependence of $v_2$ for all hadrons studied provides evidence for the onset of dominant partonic interactions by ${\sqrt{s_{_{\rm{NN}}}}}$ = 4.5 GeV.
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Submitted 11 August, 2025; v1 submitted 2 April, 2025;
originally announced April 2025.
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Measurement of Kaon Directed Flow in Au+Au Collisions in the High Baryon Density Region
Authors:
STAR Collaboration,
B. E. Aboona,
J. Adam,
G. Agakishiev,
I. Aggarwal,
M. M. Aggarwal,
Z. Ahammed,
A. Aitbayev,
I. Alekseev,
E. Alpatov,
A. K. Alshammri,
A. Aparin,
S. Aslam,
J. Atchison,
G. S. Averichev,
V. Bairathi,
X. Bao,
P. Barik,
K. Barish,
S. Behera,
P. Bhagat,
A. Bhasin,
S. Bhatta,
I. G. Bordyuzhin,
J. D. Brandenburg
, et al. (363 additional authors not shown)
Abstract:
Rapidity-odd directed flow $v_1$ measurements are presented for $K^{\pm}$ and $K^0_S$ in Au$+$Au collisions at $\sqrt{s_{\text{NN}}}$ = 3.0, 3.2, 3.5, and 3.9 GeV with the STAR experiment. For comparison, $v_1$ of $π^{\pm}$, protons, and $Λ$ from the same collisions are also discussed. The mid-rapidity $v_1$ slope $\text{d}v_1/\text{d}y|_{y=0}$ for protons and $Λ$ is positive in these collisions.…
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Rapidity-odd directed flow $v_1$ measurements are presented for $K^{\pm}$ and $K^0_S$ in Au$+$Au collisions at $\sqrt{s_{\text{NN}}}$ = 3.0, 3.2, 3.5, and 3.9 GeV with the STAR experiment. For comparison, $v_1$ of $π^{\pm}$, protons, and $Λ$ from the same collisions are also discussed. The mid-rapidity $v_1$ slope $\text{d}v_1/\text{d}y|_{y=0}$ for protons and $Λ$ is positive in these collisions. On the other hand, $v_1$ slope of kaons exhibits a strong $p_\text{T}$ dependence: negative at $p_\text{T} <$ 0.6 GeV/$c$ and positive at higher $p_\text{T}$. A similar $p_\text{T}$ dependence is also evident for the $v_1$ slope of charged pions. Compared to the spectator-removed calculations in Au$+$Au collisions at $\sqrt{s_{\text{NN}}} =$ 3.0-3.9 GeV, the JAM model demonstrates a pronounced shift of the $v_1$ slopes of mesons towards the negative direction. It suggests that the shadowing effect of the spectators plays an important role in the observed kaon anti-flow at low $p_\text{T}$ in the high baryon density region of non-central collisions.
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Submitted 31 May, 2026; v1 submitted 30 March, 2025;
originally announced March 2025.
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Measurement of cosmic muon-induced neutron background with ISMRAN detector in a non-reactor environment
Authors:
R. Dey,
P. K. Netrakanti,
D. K. Mishra,
S. P. Behera,
R. Sehgal,
V. Jha,
L. M. Pant
Abstract:
The Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) is an above-ground, very short baseline reactor anti-neutrino (${\overline{\ensuremathν}}_{e}$) experiment, located inside the Dhruva research reactor facility, Mumbai, India. The primary goal of the ISMRAN experiment is the indirect detection of reactor ${\overline{\ensuremathν}}_{e}$ through an inverse beta decay (IBD) process, u…
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The Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) is an above-ground, very short baseline reactor anti-neutrino (${\overline{\ensuremathν}}_{e}$) experiment, located inside the Dhruva research reactor facility, Mumbai, India. The primary goal of the ISMRAN experiment is the indirect detection of reactor ${\overline{\ensuremathν}}_{e}$ through an inverse beta decay (IBD) process, using a cluster of 90 optically segmented plastic scintillator detectors, weighing $\sim$1 ton. In this work, we present the neutron capture time response and energy deposition of neutron capture signals generated by cosmic muons in the ISMRAN geometry, and we compare these experimental results with Geant4-based Monte Carlo (MC) simulations. The obtained mean capture time of fast neutrons is 74.46 $\pm$ 5.98 $\mathrmμ$s and is comparable with the MC simulation results. The efficiency-corrected rate of muon-induced neutron background inside the ISMRAN geometry, due to the presence of a passive shielding structure of 10 cm lead followed by 10 cm borated polyethylene with a surface area of 600 $\mathrm{cm^{2}}$, deployed on top of the ISMRAN setup, is reported to be 1334 $\pm$ 64 (stat.) $\pm$ 70 (sys.) per day. This result shows good agreement with the expected background rate from MC simulations using Geant4. We also estimate the muon-induced fast-neutron rate in the ISMRAN geometry for the actual shielding configuration of 9000 $\mathrm{cm^{2}}$ surface area to be 3335 $\pm$ 160 (stat.) $\pm$ 175 (sys.) neutrons $\mathrm{day^{-1}}$ through an extrapolation, after incorporating the model dependent acceptance correction factor from the Geant4 MC simulation. Finally, using these results, we evaluate the neutron production yield due to the composite shielding in the ISMRAN geometry, which is 2.81$\times$$\mathrm{10^{-5}}$ neutrons per $μ$ per (g/$\mathrm{cm^{2}}$) at sea level.
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Submitted 23 March, 2025;
originally announced March 2025.
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Sensitivity study of a sapphire detector using Coherent Elastic Neutrino-Nucleus Scattering process
Authors:
S. P. Behera
Abstract:
The Indian Coherent Neutrino-nucleus Scattering Experiment(ICNSE) has been proposed at Bhabha Atomic Research Centre in India to measure the coherent elastic neutrino-nucleus scattering process using electron antineutrinos produced from reactors. Phenomenological studies are performed to find out the sensitivity of a sapphire detector for various fundamental physics parameters at an exposure of on…
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The Indian Coherent Neutrino-nucleus Scattering Experiment(ICNSE) has been proposed at Bhabha Atomic Research Centre in India to measure the coherent elastic neutrino-nucleus scattering process using electron antineutrinos produced from reactors. Phenomenological studies are performed to find out the sensitivity of a sapphire detector for various fundamental physics parameters at an exposure of one year. Reactors of different core compositions, sizes, and thermal powers have been considered as sources of electron antineutrinos. The potential of the ICNSE to measure the weak mixing angle at a low energy regime has been extracted. Furthermore, the detector's capability has been investigated for examining the electromagnetic properties of neutrinos, including their magnetic moment. Additionally, an exploration has been conducted on the detector's sensitivity in restricting new interactions between neutrinos and electrons or nuclei, thereby constraining the parameter space related to light mediators. It is found that the ICNSE detector can put a stronger constraints on the scalar and vector mediators masses.
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Submitted 27 March, 2025; v1 submitted 14 February, 2025;
originally announced February 2025.
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MoEDAL search in the CMS beam pipe for magnetic monopoles produced via the Schwinger effect
Authors:
B. Acharya,
J. Alexandre,
S. C. Behera,
P. Benes,
B. Bergmann,
S. Bertolucci,
A. Bevan,
R. Brancaccio,
H. Branzas,
P. Burian,
M. Campbell,
S. Cecchini,
Y. M. Cho,
M. de Montigny,
A. De Roeck,
J. R. Ellis,
M. Fairbairn,
D. Felea,
M. Frank,
O. Gould,
J. Hays,
A. M. Hirt,
D. L. -J. Ho,
P. Q. Hung,
J. Janecek
, et al. (42 additional authors not shown)
Abstract:
We report on a search for magnetic monopoles (MMs) produced in ultraperipheral Pb--Pb collisions during Run-1 of the LHC. The beam pipe surrounding the interaction region of the CMS experiment was exposed to 184.07 \textmu b$^{-1}$ of Pb--Pb collisions at 2.76 TeV center-of-mass energy per collision in December 2011, before being removed in 2013. It was scanned by the MoEDAL experiment using a SQU…
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We report on a search for magnetic monopoles (MMs) produced in ultraperipheral Pb--Pb collisions during Run-1 of the LHC. The beam pipe surrounding the interaction region of the CMS experiment was exposed to 184.07 \textmu b$^{-1}$ of Pb--Pb collisions at 2.76 TeV center-of-mass energy per collision in December 2011, before being removed in 2013. It was scanned by the MoEDAL experiment using a SQUID magnetometer to search for trapped MMs. No MM signal was observed. The two distinctive features of this search are the use of a trapping volume very close to the collision point and ultra-high magnetic fields generated during the heavy-ion run that could produce MMs via the Schwinger effect. These two advantages allowed setting the first reliable, world-leading mass limits on MMs with high magnetic charge. In particular, the established limits are the strongest available in the range between 2 and 45 Dirac units, excluding MMs with masses of up to 80 GeV at 95\% confidence level.
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Submitted 25 July, 2024; v1 submitted 23 February, 2024;
originally announced February 2024.
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The Present and Future of QCD
Authors:
P. Achenbach,
D. Adhikari,
A. Afanasev,
F. Afzal,
C. A. Aidala,
A. Al-bataineh,
D. K. Almaalol,
M. Amaryan,
D. Androić,
W. R. Armstrong,
M. Arratia,
J. Arrington,
A. Asaturyan,
E. C. Aschenauer,
H. Atac,
H. Avakian,
T. Averett,
C. Ayerbe Gayoso,
X. Bai,
K. N. Barish,
N. Barnea,
G. Basar,
M. Battaglieri,
A. A. Baty,
I. Bautista
, et al. (378 additional authors not shown)
Abstract:
This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015…
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This White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015 LRP (LRP15) and identified key questions and plausible paths to obtaining answers to those questions, defining priorities for our research over the coming decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (~ 5 years) and longer term (5-10 years and beyond) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential and maintain United States leadership in QCD physics worldwide. This White Paper is organized as follows: In the Executive Summary, we detail the Recommendations and Initiatives that were presented and discussed at the Town Meeting, and their supporting rationales. Section 2 highlights major progress and accomplishments of the past seven years. It is followed, in Section 3, by an overview of the physics opportunities for the immediate future, and in relation with the next QCD frontier: the EIC. Section 4 provides an overview of the physics motivations and goals associated with the EIC. Section 5 is devoted to the workforce development and support of diversity, equity and inclusion. This is followed by a dedicated section on computing in Section 6. Section 7 describes the national need for nuclear data science and the relevance to QCD research.
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Submitted 4 March, 2023;
originally announced March 2023.
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Background measurements and detector response studies for ISMRAN experiment
Authors:
R. Dey,
P. K. Netrakanti,
D. K. Mishra,
S. P. Behera,
R. Sehgal,
V. Jha,
L. M. Pant
Abstract:
We report the measurement of the non-reactor environmental backgrounds and the detector response with the Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN), which is $\sim$1 ton detector setup by volume, consisting of 10$\times$9 (10 rows and 9 columns) Plastic Scintillator Bars (PSBs) array at BARC, Mumbai, India. ISMRAN is an above-ground anti-neutrino ($\mathrm{\overlineν_{e}}$) ex…
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We report the measurement of the non-reactor environmental backgrounds and the detector response with the Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN), which is $\sim$1 ton detector setup by volume, consisting of 10$\times$9 (10 rows and 9 columns) Plastic Scintillator Bars (PSBs) array at BARC, Mumbai, India. ISMRAN is an above-ground anti-neutrino ($\mathrm{\overlineν_{e}}$) experiment at very short baseline located at Dhruva research reactor facility. It is enclosed by a shielding made of 10 cm thick lead and 10 cm thick borated polyethylene to minimize the backgrounds and is mounted on a movable base structure, situated at $\sim$ 13 m away from the reactor core. These measurements are useful in the context of the ISMRAN detector setup that will be used to detect the reactor $\mathrm{\overlineν_{e}}$ and measure its energy spectrum through the inverse beta decay (IBD) process. In this paper, we present the energy resolution model and energy non-linearity model of PSB and the cosmogenic muon-induced background, based on the sum of their energy depositions and number of hit bars. Reconstructed sum energy spectrum and number of hit bars distribution for $\mathrm{{}^{22}Na}$ radioactive source has been compared with Geant4 based Monte Carlo simulations. These experimentally measured results will be useful for discriminating the correlated and uncorrelated background events from the true IBD events in reactor ON and OFF conditions inside the reactor hall.
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Submitted 11 January, 2023; v1 submitted 27 November, 2022;
originally announced November 2022.
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Dynamics of Hot QCD Matter -- Current Status and Developments
Authors:
Santosh K. Das,
Prabhakar Palni,
Jhuma Sannigrahi,
Jan-e Alam,
Cho Win Aung,
Yoshini Bailung,
Debjani Banerjee,
Gergely Gábor Barnaföldi,
Subash Chandra Behera,
Partha Pratim Bhaduri,
Samapan Bhadury,
Rajesh Biswas,
Pritam Chakraborty,
Vinod Chandra,
Prottoy Das,
Sadhana Dash,
Saumen Datta,
Sudipan De,
Vaishnavi Desai,
Suman Deb,
Debarshi Dey,
Jayanta Dey,
Sabyasachi Ghosh,
Najmul Haque,
Mujeeb Hasan
, et al. (42 additional authors not shown)
Abstract:
The discovery and characterization of hot and dense QCD matter, known as Quark Gluon Plasma (QGP), remains the most international collaborative effort and synergy between theorists and experimentalists in modern nuclear physics to date. The experimentalists around the world not only collect an unprecedented amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brook…
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The discovery and characterization of hot and dense QCD matter, known as Quark Gluon Plasma (QGP), remains the most international collaborative effort and synergy between theorists and experimentalists in modern nuclear physics to date. The experimentalists around the world not only collect an unprecedented amount of data in heavy-ion collisions, at Relativistic Heavy Ion Collider (RHIC), at Brookhaven National Laboratory (BNL) in New York, USA, and the Large Hadron Collider (LHC), at CERN in Geneva, Switzerland but also analyze these data to unravel the mystery of this new phase of matter that filled a few microseconds old universe, just after the Big Bang. In the meantime, advancements in theoretical works and computing capability extend our wisdom about the hot-dense QCD matter and its dynamics through mathematical equations. The exchange of ideas between experimentalists and theoreticians is crucial for the progress of our knowledge. The motivation of this first conference named "HOT QCD Matter 2022" is to bring the community together to have a discourse on this topic. In this article, there are 36 sections discussing various topics in the field of relativistic heavy-ion collisions and related phenomena that cover a snapshot of the current experimental observations and theoretical progress. This article begins with the theoretical overview of relativistic spin-hydrodynamics in the presence of the external magnetic field, followed by the Lattice QCD results on heavy quarks in QGP, and finally, it ends with an overview of experiment results.
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Submitted 29 August, 2022;
originally announced August 2022.
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Evaluation of the response of plastic scintillator bars and measurement of neutron capture time in non-reactor environment for the ISMRAN experiment
Authors:
R. Dey,
P. K. Netrakanti,
D. K. Mishra,
S. P. Behera,
R. Sehgal,
V. Jha,
L. M. Pant
Abstract:
We present a detailed study on detector response to different radioactive sources and the measurements of non-reactor environmental backgrounds with the Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) detector setup consisting of 9$\times$10 Plastic Scintillator Bars (PSBs) array at BARC, Mumbai. These measurements are useful in the context of the ISMRAN detector setup, which will b…
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We present a detailed study on detector response to different radioactive sources and the measurements of non-reactor environmental backgrounds with the Indian Scintillator Matrix for Reactor Anti-Neutrinos (ISMRAN) detector setup consisting of 9$\times$10 Plastic Scintillator Bars (PSBs) array at BARC, Mumbai. These measurements are useful in the context of the ISMRAN detector setup, which will be used to detect the reactor anti-neutrinos (${\bar{\ensuremathν}}_{e}$) and measure its energy spectra, through the inverse beta decay (IBD) process. A GEANT4 based Monte Carlo (MC) simulation is used to understand the optical transmission, energy resolution and energy non-linearity of the ISMRAN detector. A detailed analysis procedure has been developed to understand the natural radioactive, cosmogenic and cosmic muon-induced backgrounds with the ISMRAN detector setup in a non-reactor environment, based on their energy deposition, number of bars hit as well as topological event selection criteria in position and time for triggered events. Data and MC simulated distributions of reconstructed sum energy and number of bars hit has been compared for the radioactive $γ$ + positron source such as $\mathrm{{}^{22}Na}$ placed at the center of the ISMRAN array. Fast neutron energy response and capture time distribution in ISMRAN array has been studied using a novel technique involving Time of Flight (TOF) of the measured fast neutrons. The observed characteristic neutron capture time ( $τ$ ) of 68.29 $\pm$ 9.48 $μ$s is in good agreement with $\sim$65 $μ$s obtained from MC simulation. These experimentally measured results will be useful for discriminating the correlated and uncorrelated background events from the true IBD events in reactor ON and OFF conditions inside the reactor hall.
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Submitted 6 August, 2022;
originally announced August 2022.
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Measurements using a prototype array of plastic scintillator bars for reactor based electron anti-neutrino detection
Authors:
P. K. Netrakanti,
D. Mulmule,
D. K. Mishra,
S. P. Behera,
R. Dey,
R. Sehgal,
S. K. Sinha,
V. Jha,
L. M. Pant
Abstract:
We report measurement of reactor based electron anti-neutrinos from a prototype array of plastic scintillator bars ( mini-ISMRAN ) located inside Dhruva research reactor hall, BARC. The detector setup took data for 128 days for reactor on (RON) and 51 days for reactor off (ROFF) condition. A detailed analysis procedure is developed to select the anti-neutrino candidate events based on the energy d…
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We report measurement of reactor based electron anti-neutrinos from a prototype array of plastic scintillator bars ( mini-ISMRAN ) located inside Dhruva research reactor hall, BARC. The detector setup took data for 128 days for reactor on (RON) and 51 days for reactor off (ROFF) condition. A detailed analysis procedure is developed to select the anti-neutrino candidate events based on the energy deposition, number of bars hit as well as topological event selection criteria in position and time. Each of these selection criteria are compared with Monte Carlo based simulations and further an embedding technique is used to estimate the efficiencies from a data driven background study. The obtained anti-neutrino like events in RON condition are 218 $\pm$ 50 (stat) $\pm$ 37 (sys) after background subtraction. The obtained results are compared with theoretical estimation which yields 214 $\pm$ 32 (sys) anti-neutrino events for the RON condition.
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Submitted 28 December, 2021; v1 submitted 24 December, 2021;
originally announced December 2021.
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Cosmic ray measurements using the ISMRAN setup in a non-reactor environment
Authors:
S. P. Behera,
R. Sehgal,
R. Dey,
P. K. Netrakanti,
D. K. Mishra,
V. Jha,
L. M. Pant
Abstract:
The cosmic rays data collected using a large area plastic scintillator array ISMRAN (Indian Scintillator Matrix for Reactor AntiNeutrino) are presented. The data collected serve as a useful benchmark of cosmogenic background in a non-reactor environment for the future measurements of electron-antineutrinos to be performed using the ISMRAN setup. The zenith angle distribution of the atmospheric muo…
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The cosmic rays data collected using a large area plastic scintillator array ISMRAN (Indian Scintillator Matrix for Reactor AntiNeutrino) are presented. The data collected serve as a useful benchmark of cosmogenic background in a non-reactor environment for the future measurements of electron-antineutrinos to be performed using the ISMRAN setup. The zenith angle distribution of the atmospheric muons has been measured and compared with Monte Carlo expectations. The detector setup was further used to measure the lifetime distribution of stopped muons and extract their rates inside the detector matrix. The measured spectra of decaying muons and associated electrons show a good agreement with the MC simulations performed through GEANT4 simulation.
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Submitted 2 June, 2022; v1 submitted 3 November, 2021;
originally announced November 2021.
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Characterization of plastic scintillator bars using fast neutrons from D-D and D-T reactions
Authors:
R. Dey,
P. K. Netrakanti,
D. K. Mishra,
S. P. Behera,
D. Mulmule,
T. Patel,
P. S. Sarkar,
V. Jha,
L. M. Pant
Abstract:
We report results of fast neutron response in plastic scintillator (PS) bars from deuterium-deuterium (D-D) and deuterium-tritium (D-T) reactions using Purnima Neutron Generator Facility, BARC, Mumbai. These measurements are useful in context of Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) detection, an array of 10x10 PS bars, used to measure reactor anti-neutrinos through inverse…
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We report results of fast neutron response in plastic scintillator (PS) bars from deuterium-deuterium (D-D) and deuterium-tritium (D-T) reactions using Purnima Neutron Generator Facility, BARC, Mumbai. These measurements are useful in context of Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) detection, an array of 10x10 PS bars, used to measure reactor anti-neutrinos through inverse beta decay (IBD) signal. ISMRAN detector, an above-ground experiment close to the reactor core (~13m), deals with an active fast neutron background inside the reactor hall. A good understanding of fast neutron response in PS bars is an essential pre-requisite for suppression and discrimination of fast neutron background from IBD events. A monoenergetic neutron beam from the fusion reaction of D-D at 2.45 MeV and D-T at 14.1 MeV are used to characterize the energy response in these bars. The neutron energy response function has been simulated using the GEANT4 package and are compared with the measured data. A reasonable agreement of deposited energies by fast neutrons in PS bars between data and simulation are obtained for these reactions. The ratio of energy deposition in adjacent bars is used to discriminate between prompt IBD, fast neutron and neutron capture cascade gamma events.
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Submitted 4 November, 2021; v1 submitted 15 October, 2021;
originally announced October 2021.
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The Large Hadron-Electron Collider at the HL-LHC
Authors:
P. Agostini,
H. Aksakal,
S. Alekhin,
P. P. Allport,
N. Andari,
K. D. J. Andre,
D. Angal-Kalinin,
S. Antusch,
L. Aperio Bella,
L. Apolinario,
R. Apsimon,
A. Apyan,
G. Arduini,
V. Ari,
A. Armbruster,
N. Armesto,
B. Auchmann,
K. Aulenbacher,
G. Azuelos,
S. Backovic,
I. Bailey,
S. Bailey,
F. Balli,
S. Behera,
O. Behnke
, et al. (312 additional authors not shown)
Abstract:
The Large Hadron electron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy recovery technology, it collides a novel, intense electron beam with a proton or ion beam from the High Luminosity--Large Hadron Collider (HL-LHC). The accelerator and interaction region are designed for concurrent el…
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The Large Hadron electron Collider (LHeC) is designed to move the field of deep inelastic scattering (DIS) to the energy and intensity frontier of particle physics. Exploiting energy recovery technology, it collides a novel, intense electron beam with a proton or ion beam from the High Luminosity--Large Hadron Collider (HL-LHC). The accelerator and interaction region are designed for concurrent electron-proton and proton-proton operation. This report represents an update of the Conceptual Design Report (CDR) of the LHeC, published in 2012. It comprises new results on parton structure of the proton and heavier nuclei, QCD dynamics, electroweak and top-quark physics. It is shown how the LHeC will open a new chapter of nuclear particle physics in extending the accessible kinematic range in lepton-nucleus scattering by several orders of magnitude. Due to enhanced luminosity, large energy and the cleanliness of the hadronic final states, the LHeC has a strong Higgs physics programme and its own discovery potential for new physics. Building on the 2012 CDR, the report represents a detailed updated design of the energy recovery electron linac (ERL) including new lattice, magnet, superconducting radio frequency technology and further components. Challenges of energy recovery are described and the lower energy, high current, 3-turn ERL facility, PERLE at Orsay, is presented which uses the LHeC characteristics serving as a development facility for the design and operation of the LHeC. An updated detector design is presented corresponding to the acceptance, resolution and calibration goals which arise from the Higgs and parton density function physics programmes. The paper also presents novel results on the Future Circular Collider in electron-hadron mode, FCC-eh, which utilises the same ERL technology to further extend the reach of DIS to even higher centre-of-mass energies.
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Submitted 12 April, 2021; v1 submitted 28 July, 2020;
originally announced July 2020.
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Active-sterile neutrino mixing constraint using reactor antineutrinos with the ISMRAN set-up
Authors:
S. P. Behera,
D. K. Mishra,
L. M. Pant
Abstract:
In this work, we present an analysis of the sensitivity to the active-sterile neutrino mixing with the Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) experimental set-up at very short baseline. In this article, we have considered the measurement of electron antineutrino induced events employing a single detector which can be placed either at a single position or moved between near a…
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In this work, we present an analysis of the sensitivity to the active-sterile neutrino mixing with the Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) experimental set-up at very short baseline. In this article, we have considered the measurement of electron antineutrino induced events employing a single detector which can be placed either at a single position or moved between near and far positions from the given reactor core. Results extracted in the later case are independent of the theoretical prediction of the reactor anti-neutrino spectrum and detector related systematic uncertainties. Our analysis shows that the results obtained from the measurement carried out at a combination of the near and far detector positions are improved significantly at higher $Δm^{2}_{41}$ compared to the ones obtained with the measurement at a single detector position only. It is found that the best possible combination of near and far detector positions from a 100 MW$_{th}$ power DHRUVA research reactor core are 7 m and 9 m, respectively, for which ISMRAN set-up can exclude in the range 1.4 $eV^{2} \leq Δm^{2}_{41} \leq$ 4.0 $eV^{2}$ of reactor antineutrino anomaly region along with the present best-fit point of active-sterile neutrino oscillation parameters. At those combinations of detector positions, the ISMRAN set-up can observe the active sterile neutrino oscillation with a 95$\%$ confidence level provided that $\sin^{2}2θ_{14}\geq 0.09$ at $Δm^{2}_{41}$ = 1 eV$^{2}$ for an exposure of 1 ton-yr. The active-sterile neutrino mixing sensitivity can be improved by about 22\% at the same exposure by placing the detector at near and far distances of 15 m and 17 m, respectively, from the compact proto-type fast breeder reactor (PFBR) facility which has a higher thermal power of 1250 MW$_{th}$.
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Submitted 21 July, 2020; v1 submitted 1 July, 2020;
originally announced July 2020.
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Sensitivity to sterile neutrino mixing using reactor antineutrinos
Authors:
S. P. Behera,
D. K. Mishra,
L. M. Pant
Abstract:
The reactor antineutrinos are used for the precise measurement of oscillation parameters in the 3-neutrino model, and also used to investigate active-sterile neutrino mixing sensitivity in the 3$+$1 neutrino framework. In the present work, we study the feasibility of sterile neutrino search with the Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) experimental set-up using electron an…
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The reactor antineutrinos are used for the precise measurement of oscillation parameters in the 3-neutrino model, and also used to investigate active-sterile neutrino mixing sensitivity in the 3$+$1 neutrino framework. In the present work, we study the feasibility of sterile neutrino search with the Indian Scintillator Matrix for Reactor Anti-Neutrino (ISMRAN) experimental set-up using electron antineutrinos ($\overlineν_e$) produced from reactor as a source. The so-called 3$+$1 scenario is considered for active-sterile neutrino mixing, which leads to projected exclusion curves in the sterile neutrino mass and mixing angle plane. The analysis is performed considering both the reactor and detector related parameters. It is found that, the ISMRAN set-up can observe the active-sterile neutrino mixing sensitivity for $\sin^{2}2θ_{14} \geq$ 0.064 and $Δm^{2}_{41}$ = 1.0 eV$^2$ at 90$\%$ confidence level for an exposure of 1 ton-year by using neutrinos produced from the DHRUVA reactor with thermal power of 100 MW$_{th}$. It is also observed that, there is a significant improvement of the active-sterile neutrino mixing parameter $\sin^{2}2θ_{14}$ to $\sim$ 0.03 at the same $Δm^{2}_{41}$ by putting the ISMRAN detector set-up at a distance of 20 m from the compact proto-type fast breeder reactor (PFBR) facility with thermal power of 1250 MW$_{th}$.
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Submitted 4 February, 2019; v1 submitted 15 January, 2019;
originally announced January 2019.
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Measurement of the response of a liquid scintillation detector to monoenergetic electrons and neutrons
Authors:
P. C. Rout,
A. Gandhi,
T. Basak,
R. G. Thomas,
C. Ghosh,
A. Mitra,
G. Mishra,
S. P. Behera,
R. Kujur,
E. T. Mirgule,
B. K. Nayak,
A. Saxena,
Suresh Kumar,
V. M. Datar
Abstract:
The response of the liquid scintillator (EJ-301 equivalent to NE-213) to the monoenergetic electrons produced in Compton scattered $γ$-ray tagging has been carried out for various radioactive $γ$-ray sources. The measured electron response is found to be linear up to $\sim$4~MeVee and the resolution of the liquid scintillator at 1~MeVee is observed to be $\sim$~11\%. The pulse shape discrimination…
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The response of the liquid scintillator (EJ-301 equivalent to NE-213) to the monoenergetic electrons produced in Compton scattered $γ$-ray tagging has been carried out for various radioactive $γ$-ray sources. The measured electron response is found to be linear up to $\sim$4~MeVee and the resolution of the liquid scintillator at 1~MeVee is observed to be $\sim$~11\%. The pulse shape discrimination and pulse height response of the liquid scintillator for neutrons has been measured using $^7$Li(p,n$_1$)$^7$Be*(0.429 MeV) reaction. Non linear response to mono-energetic neutrons for the liquid scintillator is observed at E$_n$=5.3, 9.0 and 12.7 MeV. The measured response of the liquid scintillator for electrons and neutrons have been compared with Geant4 simulation.
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Submitted 16 May, 2017;
originally announced May 2017.
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Electromagnetic transition from the 4$^+$ to 2$^+$ resonance in $^8$Be measured via the radiative capture in $^4$He+$^4$He
Authors:
V. M. Datar,
D. R. Chakrabarty,
Suresh Kumar,
V. Nanal,
S. Pastore,
R. B. Wiringa,
S. P. Behera,
A. Chatterjee,
D. Jenkins,
C. J. Lister,
E. T. Mirgule,
A. Mitra,
R. G. Pillay,
K. Ramachandran,
O. J. Roberts,
P. C. Rout,
A. Shrivastava,
P. Sugathan
Abstract:
An earlier measurement on the 4$^+$ to 2$^+$ radiative transition in $^8$Be provided the first electromagnetic signature of its dumbbell-like shape. However, the large uncertainty in the measured cross section does not allow a stringent test of nuclear structure models. The present paper reports a more elaborate and precise measurement for this transition, via the radiative capture in the $^4$He+…
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An earlier measurement on the 4$^+$ to 2$^+$ radiative transition in $^8$Be provided the first electromagnetic signature of its dumbbell-like shape. However, the large uncertainty in the measured cross section does not allow a stringent test of nuclear structure models. The present paper reports a more elaborate and precise measurement for this transition, via the radiative capture in the $^4$He+$^4$He reaction, improving the accuracy by about a factor of three. The {\it ab initio} calculations of the radiative transition strength with improved three-nucleon forces are also presented. The experimental results are compared with the predictions of the alpha cluster model and {\it ab initio} calculations.
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Submitted 6 May, 2013;
originally announced May 2013.
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Measurement of the damping of nuclear shell effect in the doubly magic $^{208}$Pb region
Authors:
P. C. Rout,
D. R. Chakrabarty,
V. M. Datar,
Suresh Kumar,
E. T Mirgule,
A. Mitra,
V. Nanal,
S. P. Behera,
V. Singh
Abstract:
The damping of the nuclear shell effect with excitation energy has been measured through an analysis of the neutron spectra following the triton transfer in the $^7$Li induced reaction on $^{205}$Tl. The measured neutron spectra demonstrate the expected large shell correction energy for the nuclei in the vicinity of doubly magic $^{208}$Pb and a small value for $^{184}$W. A quantitative extraction…
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The damping of the nuclear shell effect with excitation energy has been measured through an analysis of the neutron spectra following the triton transfer in the $^7$Li induced reaction on $^{205}$Tl. The measured neutron spectra demonstrate the expected large shell correction energy for the nuclei in the vicinity of doubly magic $^{208}$Pb and a small value for $^{184}$W. A quantitative extraction of the allowed values of the damping parameter $γ$, along with those for the asymptotic nuclear level density parameter $\tilde{a}$, has been made for the first time.
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Submitted 14 February, 2013; v1 submitted 11 October, 2012;
originally announced October 2012.