0000000000757902
AUTHOR
W. N. Catford
showing 10 related works from this author
Radioactivity of neutron-rich oxygen fluorine and neon isotopes
1999
The $\ensuremath{\gamma}$ radiation and neutrons emitted following the $\ensuremath{\beta}$ decays of ${}^{24}\mathrm{O},$ ${}^{25--27}\mathrm{F},$ and ${}^{28\ensuremath{-}30}\mathrm{Ne}$ have been measured. The nuclides were produced in the quasifragmentation of a 2.8 GeV ${}^{36}\mathrm{S}$ beam, separated in-flight and identified through time-of-flight and energy-loss measurements. The ions were stopped in a silicon detector telescope, which was used to detect the $\ensuremath{\beta}$ particles emitted in their subsequent radioactive decay. The coincident $\ensuremath{\gamma}$ rays were measured using four large volume germanium detectors mounted close to the implantation point and the …
Shape ofAr44: Onset of deformation in neutron-rich nuclei nearCa48
2009
The development of deformation and shape coexistence in the vicinity of doubly magic $^{48}\mathrm{Ca}$, related to the weakening of the $N=28$ shell closure, was addressed in a low-energy Coulomb excitation experiment using a radioactive $^{44}\mathrm{Ar}$ beam from the SPIRAL facility at GANIL. The ${2}_{1}^{+}$ and ${2}_{2}^{+}$ states in $^{44}\mathrm{Ar}$ were excited on $^{208}\mathrm{Pb}$ and $^{109}\mathrm{Ag}$ targets at two different beam energies. $B(E2)$ values between all observed states and the spectroscopic quadrupole moment of the ${2}_{1}^{+}$ state were extracted from the differential Coulomb excitation cross sections, indicating a prolate shape of the $^{44}\mathrm{Ar}$ n…
Nucleon transfer via (d,p) using TIARA with a24Ne radioactive beam
2005
NESTER; The first physics results measured using the TIARA array are reported. The reaction $^{24}$Ne(d,p)$^{25}$Ne has been studied in inverse kinematics with a radioactive beam of $^(24)$Ne provided by SPIRAL at GANIL. TIARA is very compact with a high geometrical coverage for charged particles, and is designed specifically for the study of transfer reactions in inverse kinematics, with radioactive beams. From the (d,p) differential cross sections, the ground state of $^{25}$Ne is assigned to have $J^\pi$ = $1/2^+$ and the lowest states with $J^\pi$ = $5/2^+$ and $3/2^+$ are tentatively identified at excitation energies of 1.70 and 2.05 (±0.05) MeV, respectively. Coincident gamma-ray data…
The electronion scattering experiment ELISe at the International Facility for Antiproton and Ion Research (FAIR) - A conceptual design study
2011
The electronion scattering experiment ELISe is part of the installations envisaged at the new experimental storage ring at the International Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany. It offers an unique opportunity to use electrons as probe in investigations of the structure of exotic nuclei. The conceptual design and the scientific challenges of ELISe are presented. © 2011 Elsevier B.V. All rights reserved.
Beta-decay half-lives at the N = 28 shell closure
2004
Abstract Measurements of the beta-decay half-lives of neutron-rich nuclei (MgAr) in the vicinity of the N =28 shell closure are reported. Some 22 half-lives have been determined, 12 of which for the first time. Particular emphasis is placed on the results for the Si isotopes, the half-lives of which have been extended from N =25 to 28. Comparison with QRPA calculations suggests that 42 Si is strongly deformed. This is discussed in the light of a possible weakening of the spin–orbit potential.
Migration of Nuclear Shell Gaps Studied in thed(Ne24,pγ)Ne25Reaction
2010
The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 is put on a firm footing by confirmation of this state's identity. The raised 3/2+ level is observed simultaneously with the intruder negative parity 7/2- and 3/2- levels, providing evidence for the reduction in the N=20 gap. The coincident gamma-ray decays allowed the assignment of spins as well as the transferred orbital angular momentum. The excitation energy of the 3/2+ state shows that the estab…
First Exploration of Neutron Shell Structure below Lead and beyond N=126
2020
The nuclei below lead but with more than 126 neutrons are crucial to an understanding of the astrophysical r process in producing nuclei heavier than A∼190. Despite their importance, the structure and properties of these nuclei remain experimentally untested as they are difficult to produce in nuclear reactions with stable beams. In a first exploration of the shell structure of this region, neutron excitations in ^{207}Hg have been probed using the neutron-adding (d,p) reaction in inverse kinematics. The radioactive beam of ^{206}Hg was delivered to the new ISOLDE Solenoidal Spectrometer at an energy above the Coulomb barrier. The spectroscopy of ^{207}Hg marks a first step in improving our…
New constraints on the Al25(p,γ) reaction and its influence on the flux of cosmic γ rays from classical nova explosions
2021
The astrophysical $^{25}\mathrm{Al}(p,\ensuremath{\gamma})\phantom{\rule{0.16em}{0ex}}^{26}\mathrm{Si}$ reaction represents one of the key remaining uncertainties in accurately modeling the abundance of radiogenic $^{26}\mathrm{Al}$ ejected from classical novae. Specifically, the strengths of key proton-unbound resonances in $^{26}\mathrm{Si}$, that govern the rate of the $^{25}\mathrm{Al}(p,\ensuremath{\gamma})$ reaction under explosive astrophysical conditions, remain unsettled. Here, we present a detailed spectroscopy study of the $^{26}\mathrm{Si}$ mirror nucleus $^{26}\mathrm{Mg}$. We have measured the lifetime of the ${3}^{+}$, 6.125-MeV state in $^{26}\mathrm{Mg}$ to be $19(3)\phanto…
New constraints on the Al25(p,γ) reaction and its influence on the flux of cosmic γ rays from classical nova explosions
2021
The astrophysical 25Al(p,γ)26Si reaction represents one of the key remaining uncertainties in accurately modeling the abundance of radiogenic 26Al ejected from classical novae. Specifically, the strengths of key proton-unbound resonances in 26Si, that govern the rate of the 25Al(p,γ) reaction under explosive astrophysical conditions, remain unsettled. Here, we present a detailed spectroscopy study of the 26Si mirror nucleus 26Mg. We have measured the lifetime of the 3+, 6.125-MeV state in 26Mg to be 19(3)fs and provide compelling evidence for the existence of a 1− state in the T=1,A=26 system, indicating a previously unaccounted for ℓ=1 resonance in the 25Al(p,γ) reaction. Using the present…
New constraints on the Al 25 (p,γ) reaction and its influence on the flux of cosmic γ rays from classical nova explosions
2021
The astrophysical Al25(p,γ)Si26 reaction represents one of the key remaining uncertainties in accurately modeling the abundance of radiogenic Al26 ejected from classical novae. Specifically, the strengths of key proton-unbound resonances in Si26, that govern the rate of the Al25(p,γ) reaction under explosive astrophysical conditions, remain unsettled. Here, we present a detailed spectroscopy study of the Si26 mirror nucleus Mg26. We have measured the lifetime of the 3+, 6.125-MeV state in Mg26 to be 19(3)fs and provide compelling evidence for the existence of a 1- state in the T=1,A=26 system, indicating a previously unaccounted for=1 resonance in the Al25(p,γ) reaction. Using the presently…