-
Intruder structures in $^{32}$Si and $^{29}$Al
Authors:
J. Williams,
G. Hackman,
K. Starosta,
R. S. Lubna,
Priyanka Choudhary,
Subhrajit Sahoo,
P. C. Srivastava,
C. Andreoiu,
D. Annen,
H. Asch,
M. D. H. K. G. Badanage,
G. C. Ball,
M. Beuschlein,
H. Bidaman,
V. Bildstein,
R. J. Coleman,
A. B. Garnsworthy,
B. Greaves,
G. Leckenby,
V. Karayonchev,
M. S. Martin,
C. Natzke,
C. M. Petrache,
A. Radich,
E. Raleigh-Smith
, et al. (9 additional authors not shown)
Abstract:
We have studied $^{32}$Si and $^{29}$Al using $^{12}$C($^{22}$Ne,2p) and $^{12}$C($^{22}$Ne,$α$p) fusion-evaporation reactions. In both cases, we observed significant population of high-spin structures distinct from the ground-state yrast bands. In $^{32}$Si, most of the high-energy states feed into a $J^π = 5^-$ nanosecond isomer. In $^{29}$Al, we identified a rotor-like negative-parity band with…
▽ More
We have studied $^{32}$Si and $^{29}$Al using $^{12}$C($^{22}$Ne,2p) and $^{12}$C($^{22}$Ne,$α$p) fusion-evaporation reactions. In both cases, we observed significant population of high-spin structures distinct from the ground-state yrast bands. In $^{32}$Si, most of the high-energy states feed into a $J^π = 5^-$ nanosecond isomer. In $^{29}$Al, we identified a rotor-like negative-parity band with a $J^π = 7/2^-$ band-head. Doppler shift lifetime measurements were performed for all observed states. These results were compared to shell model calculations and interpreted in terms of proton and neutron cross-shell excitation.
△ Less
Submitted 27 June, 2025;
originally announced June 2025.
-
The 76Cu conundrum remains unsolved
Authors:
B. Olaizola,
A. Illana,
J. Benito,
D. P. Suárez-Bustamante,
G. Del Piccolo,
A. Algora,
B. Andel,
A. N. Andreyev,
M. Araszkiewicz,
Y. Ayyad,
R. A. Bark,
T. Berry,
M. J. G. Borge,
K. Chrysalidis,
T. E. Cocolios,
C. Costache,
J. G. Cubiss,
P. Van Duppen,
Z. Favier,
L. M. Fraile,
H. O. U. Fynbo,
F. Galtarossa,
G. Georgiev,
P. T. Greenless,
R. Grzywacz
, et al. (58 additional authors not shown)
Abstract:
Near the doubly-magic nucleus \nuc{Ni}{78} ($Z=28$, $N=50$), there has been a decades-long debate on the existence of a long-lived isomer in \nuc{Cu}{76}. A recent mass measurement claimed to have settled the debate, by measuring the energy of the isomer and shedding light on the structure of the nucleus. In this work, we present new, more accurate, and precise values of the half-lives of the isom…
▽ More
Near the doubly-magic nucleus \nuc{Ni}{78} ($Z=28$, $N=50$), there has been a decades-long debate on the existence of a long-lived isomer in \nuc{Cu}{76}. A recent mass measurement claimed to have settled the debate, by measuring the energy of the isomer and shedding light on the structure of the nucleus. In this work, we present new, more accurate, and precise values of the half-lives of the isomeric and ground states in \nuc{Cu}{76}. Our findings suggest that both states have very similar half-lives, in the 600-700 ms range, in disagreement with the literature values, implying that they cannot be differentiated by their decay curves. These results raise more questions than they answer, reopening the debate and showing that the structures in \nuc{Cu}{76} are still not fully understood.
△ Less
Submitted 9 May, 2025;
originally announced May 2025.
-
Investigation of the Excited States of $^{114}\mathrm{Sn}$ Using the GRIFFIN Spectrometer at TRIUMF
Authors:
N. K. Syeda,
P. Spagnoletti,
C. Andreoiu,
C. M. Petrache,
D. Annen,
R. S. Lubna,
V. Vedia,
A. Algora,
A. Babuf,
G. C. Ball,
S. Bhattacharjee,
R. Caballero-Folch,
R. Coleman,
I. Dillmann,
E. G. Fuakyei,
L. P. Gaffney,
F. H. Garcia,
A. B. Garnsworthy,
P. E. Garrett,
C. J. Griffin,
G. F. Grinyer,
G. Hackman,
R. Kanungo,
K. Kapoor,
A. Laffoley
, et al. (21 additional authors not shown)
Abstract:
The semi-magic $^{110-122}\mathrm{Sn}$ isotopes display signs of shape coexistence in their excited $0^+$ states, which, in contrast to the spherical $0^+$ ground states, are deformed. This paper investigates the nuclear structure of $^{114}\mathrm{Sn}$ using the competing $β^+$ decay and electron capture of a radioactive beam of $^{114}\mathrm{Sb}$ produced at the TRIUMF-ISAC facility using the G…
▽ More
The semi-magic $^{110-122}\mathrm{Sn}$ isotopes display signs of shape coexistence in their excited $0^+$ states, which, in contrast to the spherical $0^+$ ground states, are deformed. This paper investigates the nuclear structure of $^{114}\mathrm{Sn}$ using the competing $β^+$ decay and electron capture of a radioactive beam of $^{114}\mathrm{Sb}$ produced at the TRIUMF-ISAC facility using the GRIFFIN spectrometer. This study will allow for an in-depth understanding of the excited $0^+$ states in $^{114}\mathrm{Sn}$, by focusing on their decay patterns. In the present experiment, transitions at 856.2-keV and 1405.0-keV, which were observed in an earlier $β^+$ decay study but not placed in the $^{114}\mathrm{Sn}$ level scheme, have been assigned to the level scheme in connection to the $0^+_3$ level at 2156.0-keV. Properly assigning these transitions refines the level scheme and enhances our understanding of the nuclear structure in $^{114}\mathrm{Sn}$.
△ Less
Submitted 23 April, 2025;
originally announced April 2025.
-
Coulomb Excitation of $^{80}$Sr and the limits of the $N = Z = 40$ island of deformation
Authors:
R. Russell,
J. Heery,
J. Henderson,
R. Wadsworth,
K. Kaneko,
N. Shimizu,
T. Mizusaki,
Y. Sun,
C. Andreoiu,
D. W. Annen,
A. A. Avaa,
G. C. Ball,
V. Bildstein,
S. Buck,
C. Cousins,
A. B. Garnsworthy,
S. A. Gillespie,
B. Greaves,
A. Grimes,
G. Hackman,
R. O. Hughes,
D. G. Jenkins,
T. M. Kowalewski,
M. S. Martin,
C. Müller-Gatermann
, et al. (11 additional authors not shown)
Abstract:
The region of $N\approx Z\approx 40$ has long been associated with strongly deformed nuclear configurations. The presence of this strong deformation was recently confirmed through lifetime measurements in $N\approx Z$ Sr and Zr nuclei. Theoretically, however, these nuclei present a challenge due to the vast valence space required to incorporate all deformation driving interactions. Recent state-of…
▽ More
The region of $N\approx Z\approx 40$ has long been associated with strongly deformed nuclear configurations. The presence of this strong deformation was recently confirmed through lifetime measurements in $N\approx Z$ Sr and Zr nuclei. Theoretically, however, these nuclei present a challenge due to the vast valence space required to incorporate all deformation driving interactions. Recent state-of-the-art predictions indicate a near axial prolate deformation for $N=Z$ and $N=Z+2$ nuclei between $N=Z=36$ and $N=Z=40$. In this work we investigate the shores of this island of deformation through a sub-barrier Coulomb excitation study of the $N=Z+4$ nucleus, \textsuperscript{80}Sr. Extracting a spectroscopic quadrupole moment of $Q_s(2^+_1) = 0.45^{+0.83}_{-0.88}$~eb, we find that \textsuperscript{80}Sr is inconsistent with significant axial prolate deformation. This indicates that the predicted region of strong prolate deformation around $N=Z=40$ is tightly constrained to the quartet of nuclei: \textsuperscript{76,78}Sr and \textsuperscript{78,80}Zr.
△ Less
Submitted 15 August, 2024;
originally announced August 2024.
-
Cross-shell excited configurations in the structure of 34Si
Authors:
R. S. Lubna,
A. B. Garnsworthy,
Vandana Tripathi,
G. C. Ball,
C. R. Natzke,
M. Rocchini,
C. Andreoiu,
S. S. Bhattacharjee,
I. Dillmann,
F. H. Garcia,
S. A. Gillespie,
G. Hackman,
C. J. Griffin,
G. Leckenby,
T. Miyagi,
B. Olaizola,
C. Porzio,
M. M. Rajabali,
Y. Saito,
P. Spagnoletti,
S. L. Tabor,
R. Umashankar,
V. Vedia,
A. Volya,
J. Williams
, et al. (1 additional authors not shown)
Abstract:
The cross-shell excited states of $^{34}$Si have been investigated via $β$-decays of the $4^-$ ground state and the $1^+$ isomeric state of $^{34}$Al. Since the valence protons and valence neutrons occupy different major shells in the ground state as well as the intruder $1^+$ isomeric state of $^{34}$Al, intruder levels of $^{34}$Si are populated via allowed $β$ decays. Spin assignments to such i…
▽ More
The cross-shell excited states of $^{34}$Si have been investigated via $β$-decays of the $4^-$ ground state and the $1^+$ isomeric state of $^{34}$Al. Since the valence protons and valence neutrons occupy different major shells in the ground state as well as the intruder $1^+$ isomeric state of $^{34}$Al, intruder levels of $^{34}$Si are populated via allowed $β$ decays. Spin assignments to such intruder levels of $^{34}$Si were established through $γ$-$γ$ angular correlation analysis for the negative parity states with dominant configurations $(νd_{3/2})^{-1} \otimes (νf_{7/2})^{1}$ as well as the positive parity states with dominant configurations $(νsd)^{-2} \otimes (νf_{7/2}p_{3/2})^2$. The configurations of such intruder states play crucial roles in our understanding of the $N=20$ shell gap evolution. A configuration interaction model derived from the FSU Hamiltonian was utilized in order to interpret the intruder states in $^{34}$Si. Shell model interaction derived from a more fundamental theory with the Valence Space In Medium Similarity Renormalization Group (VS-IMSRG) method was also employed to interpret the structure of $^{34}$Si.
△ Less
Submitted 8 January, 2024;
originally announced January 2024.
-
Identifying the spin trapped character of the $^{32}$Si isomeric state
Authors:
J. Williams,
G. Hackman,
K. Starosta,
R. S. Lubna,
Priyanka Choudhary,
P. C. Srivastava,
C. Andreoiu,
D. Annen,
H. Asch,
M. D. H. K. G. Badanage,
G. C. Ball,
M. Beuschlein,
H. Bidaman,
V. Bildstein,
R. Coleman,
A. B. Garnsworthy,
B. Greaves,
G. Leckenby,
V. Karayonchev,
M. S. Martin,
C. Natzke,
C. M. Petrache,
A. Radich,
E. Raleigh-Smith,
D. Rhodes
, et al. (8 additional authors not shown)
Abstract:
The properties of a nanosecond isomer in $^{32}$Si, disputed in previous studies, depend on the evolution of proton and neutron shell gaps near the `island of inversion'. We have placed the isomer at 5505.2(2) keV with $J^π = 5^-$, decaying primarily via an $E3$ transition to the $2^+_1$ state. The $E3$ strength of 0.0841(10) W.u. is unusually small and suggests that this isomer is dominated by th…
▽ More
The properties of a nanosecond isomer in $^{32}$Si, disputed in previous studies, depend on the evolution of proton and neutron shell gaps near the `island of inversion'. We have placed the isomer at 5505.2(2) keV with $J^π = 5^-$, decaying primarily via an $E3$ transition to the $2^+_1$ state. The $E3$ strength of 0.0841(10) W.u. is unusually small and suggests that this isomer is dominated by the $(νd_{3/2})^{-1} \otimes (νf_{7/2})^{1}$ configuration, which is sensitive to the $N=20$ shell gap. A newly observed $4^+_1$ state is placed at 5881.4(13) keV; its energy is enhanced by the $Z=14$ subshell closure. This indicates that the isomer is located in a `yrast trap', a feature rarely seen at low mass numbers.
△ Less
Submitted 15 November, 2023;
originally announced November 2023.
-
Decay Spectroscopy of $^{160}$Eu: Quasiparticle Configurations of Excited States and Structure of $K^π$=$4^+$ Band-heads in $^{160}$Gd
Authors:
D. Yates,
R. Kruecken,
I. Dillmann,
P. E. Garrett,
B. Olaizola,
V. Vedia,
F. A. Ali,
C. Andreoiu,
W. Ashfield,
G. C. Ball,
Z. Beadle,
N. Bernier,
S. S. Bhattacharjee,
H. Bidaman,
V. Bildstein,
D. Bishop,
M. Bowry,
C. Burbadge,
R. Caballero-Folch,
D. Z. Chaney,
D. C. Cross,
A. Diaz Varela,
M. R. Dunlop,
R. Dunlop,
L. J. Evitts
, et al. (23 additional authors not shown)
Abstract:
\noindent \textbf{Background:} Detailed spectroscopy of neutron-rich, heavy, deformed nuclei is of broad interest for nuclear astrophysics and nuclear structure. Nuclei in the r-process path and following freeze-out region impact the resulting r-process abundance distribution, and the structure of nuclei midshell in both proton and neutron number helps to understand the evolution of subshell gaps…
▽ More
\noindent \textbf{Background:} Detailed spectroscopy of neutron-rich, heavy, deformed nuclei is of broad interest for nuclear astrophysics and nuclear structure. Nuclei in the r-process path and following freeze-out region impact the resulting r-process abundance distribution, and the structure of nuclei midshell in both proton and neutron number helps to understand the evolution of subshell gaps and large deformation in these nuclei.
\noindent \textbf{Purpose:} To improve the understanding of the nuclear structure of $^{160}$Gd, specifically the $K^π$=$4^+$ bands, as well as study the $β$-decay of $^{160}$Eu into $^{160}$Gd.
\noindent \textbf{Methods:} High-statistics decay spectroscopy of $^{160}$Gd resulting from the $β$-decay of $^{160}$Eu was collected using the GRIFFIN spectrometer at the TRIUMF-ISAC facility.
\noindent \textbf{Results:} Two new excited states and ten new transitions were observed in $^{160}$Gd. The $β$-decaying half-lives of the low- and high-spin isomer in $^{160}$Eu were determined, and the low-spin state's half-life was measured to be $t_{1/2}=26.0(8)$~s, $\sim$16\% shorter than previous measurements. Lifetimes of the two $K^π$=$4^+$ band-heads in $^{160}$Gd were measured for the first time, as well as $γ$-$γ$ angular correlations and mixing ratios of intense transitions out of those band-heads.
\noindent \textbf{Conclusions:} Lifetimes and mixing ratios suggest that the hexadecapole phonon model of the $K^π$=$4^+$ band-heads in $^{160}$Gd is preferred over a simple two-state strong mixing scenario, although further theoretical calculations are needed to fully understand these states. Additionally, the 1999.0 keV state in $^{160}$Gd heavily populated in $β$-decay is shown to have positive parity, which raises questions regarding the structure of the high-spin $β$-decaying state in $^{160}$Eu.
△ Less
Submitted 18 May, 2023;
originally announced May 2023.
-
Cross Sections of the $^{83}$Rb(p,$γ)^{84}$Sr and $^{84}$Kr(p,$γ)^{85}$Rb Reactions at Energies Characteristic of the Astrophysical $γ$ Process
Authors:
M. Williams,
B. Davids,
G. Lotay,
N. Nishimura,
T. Rauscher,
S. A. Gillespie,
M. Alcorta,
A. M. Amthor,
G. C. Ball,
S. S. Bhattacharjee,
V. Bildstein,
W. N. Catford,
D. T. Doherty,
N. E. Esker,
A. B. Garnsworthy,
G. Hackman,
K. Hudson,
A. Lennarz,
C. Natzke,
B. Olaizola,
A. Psaltis,
C. E. Svensson,
J. Williams,
D. Walter,
D. Yates
Abstract:
We have measured the cross section of the $^{83}$Rb(p,$γ)^{84}$Sr radiative capture reaction in inverse kinematics using a radioactive beam of $^{83}$Rb at incident energies of 2.4 and $2.7 A$ MeV. Prior to the radioactive beam measurement, the $^{84}$Kr(p,$γ)^{85}$Rb radiative capture reaction was measured in inverse kinematics using a stable beam of $^{84}$Kr at an incident energy of $2.7 A$ MeV…
▽ More
We have measured the cross section of the $^{83}$Rb(p,$γ)^{84}$Sr radiative capture reaction in inverse kinematics using a radioactive beam of $^{83}$Rb at incident energies of 2.4 and $2.7 A$ MeV. Prior to the radioactive beam measurement, the $^{84}$Kr(p,$γ)^{85}$Rb radiative capture reaction was measured in inverse kinematics using a stable beam of $^{84}$Kr at an incident energy of $2.7 A$ MeV. The effective relative kinetic energies of these measurements lie within the relevant energy window for the $γ$ process in supernovae. The central values of the measured partial cross sections of both reactions were found to be $0.17-0.42$ times the predictions of statistical model calculations. Assuming the predicted cross section at other energies is reduced by the same factor leads to a slightly higher calculated abundance of the $p$ nucleus $^{84}$Sr, caused by the reduced rate of the $^{84}$Sr($γ$,p)$^{83}$Rb reaction derived from the present measurement.
△ Less
Submitted 17 March, 2023;
originally announced March 2023.
-
First Evidence of Axial Shape Asymmetry and Configuration Coexistence in $^{74}$Zn: Suggestion for a Northern Extension of the $N=40$ Island of Inversion
Authors:
M. Rocchini,
P. E. Garrett,
M. Zielinska,
S. M. Lenzi,
D. D. Dao,
F. Nowacki,
V. Bildstein,
A. D. MacLean,
B. Olaizola,
Z. T. Ahmed,
C. Andreoiu,
A. Babu,
G. C. Ball,
S. S. Bhattacharjee,
H. Bidaman,
C. Cheng,
R. Coleman,
I. Dillmann,
A. B. Garnsworthy,
S. Gillespie,
C. J. Griffin,
G. F. Grinyer,
G. Hackman,
M. Hanley,
A. Illana
, et al. (19 additional authors not shown)
Abstract:
The excited states of $N=44$ $^{74}$Zn were investigated via $γ$-ray spectroscopy following $^{74}$Cu $β$ decay. By exploiting $γ$-$γ$ angular correlation analysis, the $2_2^+$, $3_1^+$, $0_2^+$ and $2_3^+$ states in $^{74}$Zn were firmly established. The $γ$-ray branching and $E2/M1$ mixing ratios for transitions de-exciting the $2_2^+$, $3_1^+$ and $2_3^+$ states were measured, allowing for the…
▽ More
The excited states of $N=44$ $^{74}$Zn were investigated via $γ$-ray spectroscopy following $^{74}$Cu $β$ decay. By exploiting $γ$-$γ$ angular correlation analysis, the $2_2^+$, $3_1^+$, $0_2^+$ and $2_3^+$ states in $^{74}$Zn were firmly established. The $γ$-ray branching and $E2/M1$ mixing ratios for transitions de-exciting the $2_2^+$, $3_1^+$ and $2_3^+$ states were measured, allowing for the extraction of relative $B(E2)$ values. In particular, the $2_3^+ \to 0_2^+$ and $2_3^+ \to 4_1^+$ transitions were observed for the first time. The results show excellent agreement with new microscopic large-scale shell-model calculations, and are discussed in terms of underlying shapes, as well as the role of neutron excitations across the $N=40$ gap. Enhanced axial shape asymmetry (triaxiality) is suggested to characterize $^{74}$Zn in its ground state. Furthermore, an excited $K=0$ band with a significantly larger softness in its shape is identified. A shore of the $N=40$ ``island of inversion'' appears to manifest above $Z=26$, previously thought as its northern limit in the chart of the nuclides.
△ Less
Submitted 14 February, 2023;
originally announced February 2023.
-
First Direct Measurement of an Astrophysical p-Process Reaction Cross Section Using a Radioactive Ion Beam
Authors:
G. Lotay,
S. A. Gillespie,
M. Williams,
T. Rauscher,
M. Alcorta,
M. Amthor,
C. A. Andreoiu,
D. Baal,
G. C. Ball,
S. S. Bhattacharjee,
H. Behnamian,
V. Bildstein,
C. Burbadge,
W. N. Catford,
D. T. Doherty,
N. E. Esker,
F. H. Garcia,
A. B. Garnsworthy,
G. Hackman,
S. Hallam,
K. A. Hudson,
S. Jazrawi,
E. Kasanda,
A. R. L. Kennington,
Y. H. Kim
, et al. (13 additional authors not shown)
Abstract:
We have performed the first direct measurement of the 83Rb(p,g) radiative capture reaction cross section in inverse kinematics using a radioactive beam of 83Rb at incident energies of 2.4 and 2.7 A MeV. The measured cross section at an effective relative kinetic energy of Ecm = 2.393 MeV, which lies within the relevant energy window for core collapse supernovae, is smaller than the prediction of s…
▽ More
We have performed the first direct measurement of the 83Rb(p,g) radiative capture reaction cross section in inverse kinematics using a radioactive beam of 83Rb at incident energies of 2.4 and 2.7 A MeV. The measured cross section at an effective relative kinetic energy of Ecm = 2.393 MeV, which lies within the relevant energy window for core collapse supernovae, is smaller than the prediction of statistical model calculations. This leads to the abundance of 84Sr produced in the astrophysical p process being higher than previously calculated. Moreover, the discrepancy of the present data with theoretical predictions indicates that further experimental investigation of p-process reactions involving unstable projectiles is clearly warranted.
△ Less
Submitted 14 September, 2021;
originally announced September 2021.
-
High-Precision Branching Ratio Measurement and Spin Assignment Implications for $^{62}$Ga Superallowed $β$ Decay
Authors:
A. D. MacLean,
A. T. Laffoley,
C. E. Svensson,
G. C. Ball,
J. R. Leslie,
C. Andreoiu,
A. Babu,
S. S. Bhattacharjee,
H. Bidaman,
V. Bildstein,
C. Burbadge,
M. Bowry,
C. Cheng,
D. S. Cross,
A. Diaz-Varela,
I. Dillmann,
M. R. Dunlop,
R. Dunlop,
L. J. Evitts,
P. Finlay,
S. Gillespie,
A. B. Garnsworthy,
P. E. Garrett,
E. Gopaul,
C. J. Griffin
, et al. (26 additional authors not shown)
Abstract:
A high-precision branching ratio measurement for the superallowed Fermi $β^{+}$ emitter $^{62}$Ga was performed with the Gamma-Ray Infrastructure for Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility at TRIUMF. The high efficiency of the GRIFFIN spectrometer allowed 63 $γ$-ray transitions, with intensities down…
▽ More
A high-precision branching ratio measurement for the superallowed Fermi $β^{+}$ emitter $^{62}$Ga was performed with the Gamma-Ray Infrastructure for Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility at TRIUMF. The high efficiency of the GRIFFIN spectrometer allowed 63 $γ$-ray transitions, with intensities down to $\approx$1 part per million (ppm) per $^{62}$Ga $β^{+}$ decay, to be placed in the level scheme of the daughter nucleus $^{62}$Zn, establishing the superallowed $β$ branching ratio for $^{62}$Ga decay to be 99.8577$^{+0.0023}_{-0.0029}\%$, a factor of 4 more precise than the previous world average. For several cascades, $γ-γ$ angular correlation measurements were performed to assign spins and/or determine the mixing ratios of transitions. In particular, the spin of the 2.342 MeV excited state in the daughter nucleus $^{62}$Zn was definitively assigned as $J = 0$. This assignment resolves a discrepancy between previous measurements and has important implications for the isospin symmetry breaking correction, $δ_{C1}$, in $^{62}$Ga superallowed Fermi $β$ decay.
△ Less
Submitted 19 November, 2020; v1 submitted 7 November, 2020;
originally announced November 2020.
-
Absence of Low-Energy Shape Coexistence in $^{80}$Ge: The Nonobservation of a Proposed Excited 0$_2^+$ Level at 639 keV
Authors:
F. H. Garcia,
C. Andreoiu,
G. C. Ball,
A. Bell,
A. B. Garnsworthy,
F. Nowacki,
C. M. Petrache,
A. Poves,
K. Whitmore,
F. A. Ali,
N. Bernier,
S. S. Bhattacharjee,
M. Bowry,
R. J. Coleman,
I. Dillmann,
I. Djianto,
A. M. Forney,
M. Gascoine,
G. Hackman,
K. G. Leach,
A. N. Murphy,
C. R. Natzke,
B. Olaizola,
K. Ortner,
E. E. Peters
, et al. (6 additional authors not shown)
Abstract:
The $^{80}$Ge structure was investigated in a high-statistics $β$-decay experiment of $^{80}$Ga using the GRIFFIN spectrometer at TRIUMF-ISAC through $γ$, $β$-$e$, $e$-$γ$ and $γ$-$γ$ spectroscopy. No evidence was found for the recently reported 0$_2^{+}$ 639-keV level suggested as evidence for low-energy shape coexistence in $^{80}$Ge. Large-scale shell model calculations performed in…
▽ More
The $^{80}$Ge structure was investigated in a high-statistics $β$-decay experiment of $^{80}$Ga using the GRIFFIN spectrometer at TRIUMF-ISAC through $γ$, $β$-$e$, $e$-$γ$ and $γ$-$γ$ spectroscopy. No evidence was found for the recently reported 0$_2^{+}$ 639-keV level suggested as evidence for low-energy shape coexistence in $^{80}$Ge. Large-scale shell model calculations performed in $^{78,80,82}$Ge place the $0^{+}_{2}$ level in $^{80}$Ge at 2\,MeV. The new experimental evidence combined with shell model predictions indicate that low-energy shape coexistence is not present in $^{80}$Ge.
△ Less
Submitted 24 October, 2020;
originally announced October 2020.
-
Direct observation of proton emission in 11Be
Authors:
Y. Ayyad,
B. Olaizola,
W. Mittig,
G. Potel,
V. Zelevinsky,
M. Horoi,
S. Beceiro-Novo,
M. Alcorta,
C. Andreoiu,
T. Ahn,
M. Anholm,
L. Atar,
A. Babu,
D. Bazin,
N. Bernier,
S. S. Bhattacharjee,
M. Bowry,
R. Caballero-Folch,
M. Cortesi,
C. Dalitz,
E. Dunling,
A. B. Garnsworthy,
M. Holl,
B. Kootte,
K. G. Leach
, et al. (8 additional authors not shown)
Abstract:
The elusive $β^-\text{p}^+$ decay was observed in $^{11}$Be by directly measuring the emitted protons and their energy distribution for the first time with the prototype Active Target Time Projection Chamber (pAT-TPC) in an experiment performed at ISAC-TRIUMF. The measured $β^-\text{p}^+$ branching ratio is orders of magnitude larger than any previous theoretical model predicted. This can be expla…
▽ More
The elusive $β^-\text{p}^+$ decay was observed in $^{11}$Be by directly measuring the emitted protons and their energy distribution for the first time with the prototype Active Target Time Projection Chamber (pAT-TPC) in an experiment performed at ISAC-TRIUMF. The measured $β^-\text{p}^+$ branching ratio is orders of magnitude larger than any previous theoretical model predicted. This can be explained by the presence of a narrow resonance in $^{11}$B above the proton separation energy.
△ Less
Submitted 24 September, 2019; v1 submitted 28 June, 2019;
originally announced July 2019.