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Experimental study of precisely selected evaporation chains in the decay of excited $^{25}$Mg
Authors:
A. Camaiani,
G. Casini,
L. Morelli,
S. Barlini,
S. Piantelli,
G. Baiocco,
M. Bini,
M. Bruno,
A. Buccola,
M. Cinausero,
M. Cicerchia,
M. D'Agostino,
M. Degelier,
D. Fabris,
C. Frosin,
F. Gramegna,
F. Gulminelli,
G. Mantovani,
T. Marchi,
A. Olmi,
P. Ottanelli,
G. Pasquali,
G. Pastore,
S. Valdre,
G. Verde
Abstract:
The reaction $^{12}$C + $^{13}$C at 95 MeV bombarding energy is studied using the GARFIELD + Ring Counter apparatus located at the INFN Laboratori Nazionali di Legnaro. In this paper we want to investigate the de-excitation of $^{25}$Mg aiming both at a new stringent test of the statistical description of nuclear decay and a direct comparison with the decay of the system $^{24}$Mg formed through…
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The reaction $^{12}$C + $^{13}$C at 95 MeV bombarding energy is studied using the GARFIELD + Ring Counter apparatus located at the INFN Laboratori Nazionali di Legnaro. In this paper we want to investigate the de-excitation of $^{25}$Mg aiming both at a new stringent test of the statistical description of nuclear decay and a direct comparison with the decay of the system $^{24}$Mg formed through $^{12}$C+$^{12}$C reactions previously studied. Thanks to the large acceptance of the detector and to its good fragment identification capabilities, we could apply stringent selections on fusion-evaporation events, requiring their completeness in charge. The main decay features of the evaporation residues and of the emitted light particles are overall well described by a pure statistical model; however, as for the case of the previously studied 24Mg, we observed some deviations in the branching ratios, in particular for those chains involving only the evaporation of $α$ particles. From this point of view the behavior of the $^{24}$Mg and $^{25}$Mg decay cases appear to be rather similar. An attempt to obtain a full mass balance even without neutron detection is also discussed.
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Submitted 1 October, 2020; v1 submitted 17 April, 2018;
originally announced April 2018.
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Charged particle decay of hot and rotating $^{88}$Mo nuclei in fusion-evaporation reactions
Authors:
S. Valdré,
S. Piantelli,
G. Casini,
S. Barlini,
S. Carboni,
M. Ciemała,
M. Kmiecik,
A. Maj,
K. Mazurek,
M. Cinausero,
F. Gramegna,
V. L. Kravchuk,
L. Morelli,
T. Marchi,
G. Baiocco,
L. Bardelli,
P. Bednarczyk,
G. Benzoni,
M. Bini,
N. Blasi,
A. Bracco,
S. Brambilla,
M. Bruno,
F. Camera,
A. Chbihi
, et al. (26 additional authors not shown)
Abstract:
A study of fusion-evaporation and (partly) fusion-fission channels for the $^{88}$Mo compound nucleus, produced at different excitation energies in the reaction $^{48}$Ti + $^{40}$Ca at 300, 450 and 600 MeV beam energies, is presented. Fusion-evaporation and fusion-fission cross sections have been extracted and compared with the existing systematics. Experimental data concerning light charged part…
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A study of fusion-evaporation and (partly) fusion-fission channels for the $^{88}$Mo compound nucleus, produced at different excitation energies in the reaction $^{48}$Ti + $^{40}$Ca at 300, 450 and 600 MeV beam energies, is presented. Fusion-evaporation and fusion-fission cross sections have been extracted and compared with the existing systematics. Experimental data concerning light charged particles have been compared with the prediction of the statistical model in its implementation in the Gemini++ code, well suited even for high spin systems, in order to tune the main model parameters in a mass region not abundantly covered by exclusive experimental data. Multiplicities for light charged particles emitted in fusion evaporation events are also presented. Some discrepancies with respect to the prediction of the statistical model have been found for forward emitted $α$-particles; they may be due both to pre-equilibrium emission and to reaction channels (such as Deep Inelastic Collisions, QuasiFission/QuasiFusion) different from the compound nucleus formation.
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Submitted 10 September, 2015;
originally announced September 2015.
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Non-statistical decay and $α$-correlations in the $^{12}$C+$^{12}$C fusion-evaporation reaction at 95 MeV
Authors:
L. Morelli,
G. Baiocco,
M. D'Agostino,
F. Gulminelli,
M. Bruno,
U. Abbondanno,
S. Appannababu,
S. Barlini,
M. Bini,
G. Casini,
M. Cinausero,
M. Degerlier,
D. Fabris,
N. Gelli,
F. Gramegna,
V. L. Kravchuk,
T. Marchi,
G. Pasquali,
S. Piantelli,
S. Valdré,
Ad R. Raduta
Abstract:
Multiple alpha coincidence and correlations are studied in the reaction $^{12}$C+$^{12}$C at 95 MeV for fusion-evaporation events completely detected in charge. Two specific channels with Carbon and Oxygen residues in coincidence with $α$-particles are addressed, which are associated with anomalously high branching ratios with respect the predictions by Hauser-Feshbach calculations. Triple alpha e…
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Multiple alpha coincidence and correlations are studied in the reaction $^{12}$C+$^{12}$C at 95 MeV for fusion-evaporation events completely detected in charge. Two specific channels with Carbon and Oxygen residues in coincidence with $α$-particles are addressed, which are associated with anomalously high branching ratios with respect the predictions by Hauser-Feshbach calculations. Triple alpha emission appears kinematically compatible with a sequential emission from a highly excited Mg. The phase space distribution of $α$-$α$ coincidences suggests a correlated emission from a Mg compound, leaving an Oxygen residue excited above the threshold for neutron decay. These observations indicate a preferential $α$ emission of $^{24}$Mg at excitation energies well above the threshold for $6-α$ decay.
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Submitted 14 April, 2014;
originally announced April 2014.
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Thermal properties of light nuclei from $^{12}$C+$^{12}$C fusion-evaporation reactions
Authors:
L Morelli,
G Baiocco,
M D'Agostino,
F Gulminelli,
M Bruno,
U Abbondanno,
S Appannababu,
S Barlini,
M Bini,
G Casini,
M Cinausero,
M Degerlier,
D Fabris,
N Gelli,
F Gramegna,
V L Kravchuk,
T Marchi,
G Pasquali,
S Piantelli,
S Valdré,
Ad R Raduta
Abstract:
The $^{12}$C+$^{12}$C reaction at 95 MeV has been studied through the complete charge identification of its products by means of the GARFIELD+RCo experimental set-up at INFN Laboratori Nazionali di Legnaro (LNL). In this paper, the first of a series of two, a comparison to a dedicated Hauser-Feshbach calculation allows to select a set of dissipative events which corresponds, to a large extent, to…
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The $^{12}$C+$^{12}$C reaction at 95 MeV has been studied through the complete charge identification of its products by means of the GARFIELD+RCo experimental set-up at INFN Laboratori Nazionali di Legnaro (LNL). In this paper, the first of a series of two, a comparison to a dedicated Hauser-Feshbach calculation allows to select a set of dissipative events which corresponds, to a large extent, to the statistical evaporation of highly excited $^{24}$Mg. Information on the isotopic distribution of the evaporation residues in coincidence with their complete evaporation chain is also extracted. The set of data puts strong constraints on the behaviour of the level density of light nuclei above the threshold for particle emission. In particular, a fast increase of the level density parameter with excitation energy is supported by the data. Residual deviations from a statistical behaviour are seen in two specific channels, and tentatively associated with a contamination from direct reactions and/or $α$-clustering effects. These channels are studied in further details in the second paper of the series.
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Submitted 14 April, 2014;
originally announced April 2014.
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Pre-equilibrium α-particle emission as a probe to study α-clustering in nuclei
Authors:
O. V. Fotina,
S. A. Goncharov,
D. O. Eremenko,
S. Yu. Platonov,
O. A. Yuminov,
V. L. Kravchuk,
F. Gramegna,
T. Marchi,
M. Cinausero,
M. D'Agostino,
M. Bruno,
G. Baiocco,
L. Morelli,
M. Degerlier,
G. Casini,
S. Barlini,
S. Valdrè,
S. Piantelli,
G. Pasquali,
A. Bracco,
F. Camera,
O. Wieland,
G. Benzoni,
N. Blasi,
A. Giaz
, et al. (2 additional authors not shown)
Abstract:
A theoretical approach was developed to describe secondary particle emission in heavy ion collisions, with special regards to pre-equilibrium α-particle production. Griffin's model of non-equilibrium processes is used to account for the first stage of the compound system formation, while a Monte Carlo statistical approach was used to describe the further decay from a hot source at thermal equilibr…
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A theoretical approach was developed to describe secondary particle emission in heavy ion collisions, with special regards to pre-equilibrium α-particle production. Griffin's model of non-equilibrium processes is used to account for the first stage of the compound system formation, while a Monte Carlo statistical approach was used to describe the further decay from a hot source at thermal equilibrium. The probabilities of neutron, proton and α-particle emission have been evaluated for both the equilibrium and pre-equilibrium stages of the process. Fission and γ-ray emission competition were also considered after equilibration. Effects due the possible cluster structure of the projectile which has been excited during the collisions have been experimentally evidenced studying the double differential cross sections of p and α-particles emitted in the E=250MeV 16O +116Sn reaction. Calculations within the present model with different clusterization probabilities have been compared to the experimental data.
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Submitted 2 October, 2013;
originally announced October 2013.
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GARFIELD + RCo Digital Upgrade: a Modern Set-up for Mass and Charge Identification of Heavy Ion Reaction Products
Authors:
M. Bruno,
F. Gramegna,
T. Marchi,
L. Morelli,
G. Pasquali,
G. Casini,
U. Abbondanno,
G. Baiocco,
L. Bardelli,
S. Barlini,
M. Bini,
S. Carboni,
M. Cinausero,
M. D Agostino,
M. Degerlier,
V. L. Kravchuk,
E. Geraci,
P. F. Mastinu,
A. Ordine,
S. Piantelli,
G. Poggi,
A. Moroni
Abstract:
An upgraded GARFIELD + Ring Counter (RCo) apparatus is presented with improved performances as far as electronics and detectors are concerned. On one side fast sampling digital read out has been extended to all detectors, allowing for an important simplification of the signal processing chain together with an enriched extracted information. On the other side a relevant improvement has been made in…
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An upgraded GARFIELD + Ring Counter (RCo) apparatus is presented with improved performances as far as electronics and detectors are concerned. On one side fast sampling digital read out has been extended to all detectors, allowing for an important simplification of the signal processing chain together with an enriched extracted information. On the other side a relevant improvement has been made in the forward part of the setup (RCo): an increased granularity of the CsI(Tl) crystals and a higher homogeneity in the silicon detector resistivity. The renewed performances of the GARFIELD + RCo array make it suitable for nuclear reaction measurements both with stable and with Radioactive Ion Beams (RIB), like the ones foreseen for the SPES facility, where the Physics of Isospin can be studied.
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Submitted 21 September, 2013;
originally announced September 2013.
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Measurement of light charged particles in the decay channels of medium-mass excited compound nuclei
Authors:
S. Valdre',
S. Barlini,
G. Casini,
G. Pasquali,
S. Piantelli,
S. Carboni,
M. Cinausero,
F. Gramegna,
T. Marchi,
G. Baiocco,
L. Bardelli,
G. Benzoni,
M. Bini,
N. Blasi,
A. Bracco,
S. Brambilla,
M. Bruno,
F. Camera,
A. Corsi,
F. Crespi,
M. D Agostino,
M. Degerlier,
V. L. Kravchuk,
S. Leoni,
B. Million
, et al. (19 additional authors not shown)
Abstract:
The 48Ti on 40Ca reactions have been studied at 300 and 600 MeV focusing on the fusion-evaporation (FE) and fusion-fission (FF) exit channels. Energy spectra and multiplicities of the emitted light charged particles have been compared to Monte Carlo simulations based on the statistical model. Indeed, in this mass region (A about 100) models predict that shape transitions can occur at high spin val…
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The 48Ti on 40Ca reactions have been studied at 300 and 600 MeV focusing on the fusion-evaporation (FE) and fusion-fission (FF) exit channels. Energy spectra and multiplicities of the emitted light charged particles have been compared to Monte Carlo simulations based on the statistical model. Indeed, in this mass region (A about 100) models predict that shape transitions can occur at high spin values and relatively scarce data exist in the literature about coincidence measurements between evaporation residues and light charged particles. Signals of shape transitions can be found in the variations of the lineshape of high energy gamma rays emitted from the de-excitation of GDR states gated on different region of angular momenta. For this purpose it is important to keep under control the FE and FF processes, to regulate the statistical model parameters and to control the onset of possible preequilibrium emissions from 300 to 600 MeV bombarding energy.
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Submitted 9 September, 2013;
originally announced September 2013.
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Probing the statistical decay and alpha-clustering effects in 12c+12c and 14n+10b reactions
Authors:
Luca Morelli,
G. Baiocco,
M. D Agostino,
M. Bruno,
F. Gulminelli,
M. Cinausero,
M. Degerlier,
D. Fabris,
F. Gramegna,
T. Marchi,
S. Barlini,
M. Bini,
G. Casini,
N. Gelli,
A. Lopez,
G. Pasquali,
S. Piantelli,
S. Valdre'
Abstract:
An experimental campaign has been undertaken at INFN Laboratori Nazionali di Legnaro, Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. A first reaction 12C+12C at 7.9 AMeV beam energy has been measured, using the GARFIELD+Ring Counte…
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An experimental campaign has been undertaken at INFN Laboratori Nazionali di Legnaro, Italy, in order to progress in our understanding of the statistical properties of light nuclei at excitation energies above particle emission threshold, by measuring exclusive data from fusion-evaporation reactions. A first reaction 12C+12C at 7.9 AMeV beam energy has been measured, using the GARFIELD+Ring Counter experimental setup. Fusion-evaporation events have been exclusively selected. The comparison to a dedicated Hauser-Feshbach calculation allows us to give constraints on the nuclear level density at high excitation energy for light systems ranging from C up to Mg. Out-of-equilibrium emission has been evidenced and attributed both to entrance channel effects favoured by the cluster nature of reaction partners and, in more dissipative events, to the persistence of cluster correlations well above the 24Mg threshold for 6 alphas decay. The 24Mg compound nucleus has been studied with a new measurement 14N + 10B at 5.7 AMeV. The comparison between the two datasets would allow us to further constrain the level density of light nuclei. Deviations from a statistical behaviour can be analyzed to get information on nuclear clustering.
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Submitted 2 September, 2013;
originally announced September 2013.
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α-clustering effects in dissipative 12C+12C reactions at 95 MeV
Authors:
G. Baiocco,
L. Morelli,
F. Gulminelli,
M. D'Agostino,
M. Bruno,
U. Abbondanno,
S. Barlini,
M. Bini,
S. Carboni,
G. Casini,
M. Cinausero,
M. Degerlier F. Gramegna,
V. L. Kravchuk,
T. Marchi,
A. Olmi,
G. Pasquali,
S. Piantelli,
Ad. R. Raduta
Abstract:
Dissipative 12C+12C reactions at 95 MeV are fully detected in charge with the GARFIELD and RCo apparatuses at LNL. A comparison to a dedicated Hauser-Feshbach calculation allows to select events which correspond, to a large extent, to the statistical evaporation of highly excited 24Mg, as well as to extract information on the isotopic distribution of the evaporation residues in coincidence with th…
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Dissipative 12C+12C reactions at 95 MeV are fully detected in charge with the GARFIELD and RCo apparatuses at LNL. A comparison to a dedicated Hauser-Feshbach calculation allows to select events which correspond, to a large extent, to the statistical evaporation of highly excited 24Mg, as well as to extract information on the isotopic distribution of the evaporation residues in coincidence with their complete evaporation chain. Residual deviations from a statistical behaviour are observed in αyields and attributed to the persistence of cluster correlations well above the 24Mg threshold for 6 α's decay.
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Submitted 25 January, 2013;
originally announced January 2013.