12C(p,p′) scattering measurement at forward angles

Experimental method of measuring inelastic proton scattering with high-resolution at forward angles including zero degrees has been developed. An energy resolution of 20 keV and a scattering angle resolution of 0.5 degrees have been achieved as well as low background condition and a reliable background subtraction method. The experimental technique was applied to the 12 C (p,p′) reaction for studying the property of the second 0+ state at 7.7 MeV and a broad bump around Ex~10 MeV , where the presence of a 2+ state was reported from the 12 C (α,α′) measurement. Preliminary spectra and angular distributions are shown.

New neutron-deficient isotopes from $^{78}$Kr fragmentation

In an experiment with the BigRIPS separator at the RIKEN Nishina Center, the fragmentation of a $^{78}$Kr beam allowed the observation of new neutron-deficient isotopes at the proton drip-line. Clean identification spectra could be produced and $^{63}$Se, $^{67}$Kr, and $^{68}$Kr were identified for the first time. In addition, $^{59}$Ge was also observed. Three of these isotopes, $^{59}$Ge, $^{63}$Se, and $^{67}$Kr, are potential candidates for ground-state two-proton radioactivity. In addition, the isotopes $^{58}$Ge, $^{62}$Se, and $^{66}$Kr were also sought but without success. The present experiment also allowed the determination of production cross sections for some of the most exotic…

Observation of the 2+ isomer in Co52

We report the first observation of the ${2}^{+}$ isomer in $^{52}\mathrm{Co}$, produced in the $\ensuremath{\beta}$ decay of the ${0}^{+}$, $^{52}\mathrm{Ni}$ ground state. We have observed three $\ensuremath{\gamma}$ rays at 849, 1910, and 5185 keV characterizing the $\ensuremath{\beta}$ de-excitation of the isomer. We have measured a half-life of 102(6) ms for the isomeric state. The Fermi and Gamow-Teller transition strengths for the $\ensuremath{\beta}$ decay of $^{52m}\mathrm{Co}$ to $^{52}\mathrm{Fe}$ have been determined. We also add new information on the $\ensuremath{\beta}$ decay of the ${6}^{+}$, $^{52}\mathrm{Co}$ ground state, for which we have measured a half-life of 112(3) ms.

β−-delayed spectroscopy of neutron-rich tantalum nuclei: Shape evolution in neutron-rich tungsten isotopes

The low-lying structure of W-188,W-190,W-192 has been studied following beta decays of the neutron-rich mother nuclei Ta-188,Ta-190,Ta-192 produced following the projectile fragmentation of a 1-GeV-per-nucleon Pb-208 primary beam on a natural beryllium target at the GSI Fragment Separator. The beta-decay half-lives of Ta-188, Ta-190, and Ta-192 have been measured, with gamma-ray decays of low-lying states in their respective W daughter nuclei, using heavy-ion beta-gamma correlations and a position-sensitive silicon detector setup. The data provide information on the low-lying excited states in W-188, W-190, and W-192, which highlight a change in nuclear shape at W-190 compared with that of …

Studying the Exotic Decay $^{70}Kr$ $\rightarrow$ $^{70}Br$

Acta physica Polonica / B 51(3), 587 (2020). doi:10.5506/APhysPolB.51.587

Pygmy dipole resonance in208Pb

Scattering of protons of several hundred MeV is a promising new spectroscopic tool for the study of electric dipole strength in nuclei. A case study of 208Pb shows that at very forward angles J^pi = 1- states are strongly populated via Coulomb excitation. A separation from nuclear excitation of other modes is achieved by a multipole decomposition analysis of the experimental cross sections based on theoretical angular distributions calculated within the quasiparticle-phonon model. The B(E1) transition strength distribution is extracted for excitation energies up to 9 MeV, i.e., in the region of the so-called pygmy dipole resonance (PDR). The Coulomb-nuclear interference shows sensitivity to…

Gamow-Teller Transitions Studied in ([sup 3]He, t) Reaction and Analogous β decay

Due to the simplicity of the στ operator that causes Gamow‐Teller (GT) transitions, they are the most popular nuclear weak process in the Universe. The GT transitions in pf‐shell nuclei, for example, starting from stable Tz = +1 and proton‐rich Tz = +1 nuclei, where Tz = (N−Z)/2, play important roles in the supernova‐explosion or rp‐process nucleosynthesis. In the β‐decay study of pf‐shell nuclei, half‐lives can be measured rather accurately. On the other hand, in a high‐resolution (3He, t) charge‐exchange reaction at 0°, individual GT transitions up to high excitations can be studied. In order to derive reliable GT transition strengths B(GT), we present a unique analysis that combines the …

Gamow-Teller Transitions Starting from T[sub z] = +3∕2 Nucleus [sup 47]Ti

Gamow‐Teller (GT) transitions are mediated by the στ operator. Owing to its simplicity and also its spin‐isospin nature, GT transitions play key roles in the studies of nuclear structure as well as astro‐nuclear processes. In violent neutrino‐induced reactions at the core‐collapse stage of type II supernovae, Gamow‐Teller (GT) transitions starting from stable as well as unstable pf‐shell nuclei play important roles. We study GT transitions starting from 47Ti in a high‐resolution (3He,t) charge‐exchange reactions at 0° and at an intermediate incident energy of 140 MeV/nucleon at Research Center for Nuclear Physics (RCNP), Osaka. Individual GT transitions up to high excitations were observed.…

β-Delayed and isomer spectroscopy of neutron-rich Ta and W isotopes

Decays of neutron-rich A ~ 190 nuclei have been studied following projectile fragmentation of a 208Pb beam on a 9Be target at the GSI Fragment Separator. Gamma-ray decays from previously reported isomeric states in 188Ta, 190W and 192, 193Re were used as internal calibrations for the particle identification analysis, together with the identification of previously unreported isomeric decays in 189Ta and 191W. The current work also identifies β-delayed γ rays following the decay of 188Ta to 188W for the first time. Algora, Alejandro, Alejandro.Algora@ific.uv.es ; Molina Palacios, Francisco Manuel, Francisco.Molina@ific.uv.es; Rubio Barroso, Berta, Berta.Rubio@ific.uv.es

Complete dipole response in [sup 208]Pb from high-resolution polarized proton scattering at 0°

At the Research Center for Nuclear Physics, Osaka, Japan, the 208Pb(p,p´) reaction was measured at Ep=295 MeV and scattering angles Θlab= 0° - 10°. A high energy resolution of the order of ΔE/E ≈ 8x10^-5 was achieved, corresponding to ΔE=25-30 keV (FWHM). Cross sections were extracted by a multipole decomposition analysis of the angular distributions. Dominant contributions at very forward angles originate from E1 excitation due to Coulomb projectile-target interaction and spin M1 transitions caused by the spin-isospin part of the proton-nucleus interaction. A separation of these contributions was performed with two independent methods, viz. a multipole decomposition of the angular distribu…

Nuclear weak response from the combined study of beta-decay and charge-exchange reaction

Studying the weak nuclear response, especially the Gamow-Teller (GT) transitions, of stable as well as unstable pf-shell nuclei, is one of the key issues in nuclear and astro-nuclear physics. We study the decay half-lives and the GT transitions starting from Tz = ±1 and ±2 mirror nuclei, respectively, by means of β decays and complementary hadronic (3 He , t) charge-exchange reactions. Under the assumption that isospin is a good quantum number, symmetry is expected for mirror nuclei and the GT transitions starting from the mirror nuclei. The half-lives and branching ratios and the measured strength distributions of GT transitions are compared and also combined for the understanding of the …

Comparison of T[sub z] = ±1→0 GT Transitions

Gamow‐Teller (GT) transitions can be studied in both β‐decay and charge exchange(CE) reactions. If isospin is a good quantum number, then the Tz = −1→0 and Tz = +1→0 GT mirror transitions, are identical. Therefore, a comparison of the results from studies of β decay and CE should shed light on this assumption. Accordingly we have studied the β decay of the Tz = −1 fp‐shell nuclei, 54Ni, 50Fe, 46Cr, and 42Ti, produced in fragmentation and we have compared our results with the spectra from (3He, t) measurements on the mirror Tz = +1 target nuclei studied in high resolution at RCNP, Osaka. The β‐decay experiments were performed as part of the STOPPED beam RISING campaign at GSI.

Total absorption spectroscopy of 58Cu decay

The β decay of 58Cu has been studied by means of total absorption γ-ray spectroscopy. The β feeding to the 58Ni states has been measured, and the strength of the 58Cu(1+) →58Ni(0+) Gamow-Teller transition has been determined with improved accuracy.

High-resolution (3He,t) reaction on the double-βdecaying nucleus136Xe

A (${}^{3}\text{He},t$) charge-exchange reaction experiment on the double-beta decaying nucleus ${}^{136}$Xe has been performed at an incident energy of 420 MeV with the objective to measure the Gamow-Teller (GT) strength distribution in ${}^{136}$Cs. The measurements have been carried out at the dispersion-matched WS beam line and the Grand Raiden spectrometer of the Research Center for Nuclear Physics in Osaka, where an energy resolution of 42 keV was achieved. A new gas cell with thin windows made of polyethylene naphthalate has been employed as a target. The extracted GT strength distribution is confronted with the rather long $2\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$ deca…

Multipleβ−decaying states in194Re: Shape evolution in neutron-rich osmium isotopes

decays from heavy, neutron-rich nuclei with A∼190 have been investigated following their production via the relativistic projectile fragmentation of an E/A=1 GeV 208Pb primary beam on a ∼2.5 g/cm2 9Be target. The reaction products were separated and identified using the GSI FRagment Separator (FRS) and stopped in the RISING active stopper. γ decays were observed and correlated with these secondary ions on an event-by-event basis such that γ-ray transitions following from both internal (isomeric) and β decays were recorded. A number of discrete, β-delayed γ-ray transitions associated with β decays from 194Re to excited states in 194Os have been observed, including previously reported decays …

Beta decay of the exotic Tz = - 2, $^{56}$Zn nucleus and half-life of various proton-rich Tz = -1 nuclei

Expérience GANIL/LISE3/EXOGAM; International audience; Preliminary results of an experimental study of the beta -decay of the exotic T$_z$ = - 2, $^{56}$Zn nucleus and other proton-rich T$_z$ = -1 nuclei are presented. The ions were produced at GANIL using fragmentation reactions, separated by the LISE3 spectrometer and implanted in a double-sided silicon strip detector surrounded by Ge detectors. The half-lives of $^{56}$Zn and four T$_z$ = -1 nuclei in the fp-shell have been measured. While the decay of the T$_z$ = -1 nuclei proceeds essentially by -delayed gamma emission, in the case of $^{56}$Zn -delayed proton emission is also observed. Moreover, the exotic -delayed gamma-proton decay …

The (150)Nd((3)He,t) and (150)Sm(t,(3)He) reactions with applications to beta beta decay of (150)Nd

The Nd-150(3He,t) reaction at 140 MeV/u and Sm-150(t,He-3) reaction at 115 MeV/u were measured, populating excited states in Pm-150. The transitions studied populate intermediate states of importance for the (neutrinoless) beta beta decay of Nd-150 to Sm-150. Monopole and dipole contributions to the measured excitation-energy spectra were extracted by using multipole decomposition analyses. The experimental results were compared with theoretical calculations obtained within the framework of the quasiparticle random-phase approximation, which is one of the main methods employed for estimating the half-life of the neutrinoless beta beta decay (0 nu beta beta) of Nd-150. The present results th…

Experimental study of Gamow-Teller transitions via the high-energy-resolution O18(He3,t)F18 reaction: Identification of the low-energy “super” -Gamow-Teller state

XIPE: the x-ray imaging polarimetry explorer

XIPE, the X-ray Imaging Polarimetry Explorer, is a mission dedicated to X-ray Astronomy. At the time of writing XIPE is in a competitive phase A as fourth medium size mission of ESA (M4). It promises to reopen the polarimetry window in high energy Astrophysics after more than 4 decades thanks to a detector that efficiently exploits the photoelectric effect and to X-ray optics with large effective area. XIPE uniqueness is time-spectrally-spatially- resolved X-ray polarimetry as a breakthrough in high energy astrophysics and fundamental physics. Indeed the payload consists of three Gas Pixel Detectors at the focus of three X-ray optics with a total effective area larger than one XMM mirror bu…

Two-Proton Radioactivity ofKr67

In an experiment with the BigRIPS separator at the RIKEN Nishina Center, we observed two-proton (2p) emission from 67Kr. At the same time, no evidence for 2p emission of 59Ge and 63Se, two other potential candidates for this exotic radioactivity, could be observed. This observation is in line with Q value predictions which pointed to 67Kr as being the best new candidate among the three for two-proton radioactivity. 67Kr is only the fourth 2p ground-state emitter to be observed with a half-life of the order of a few milliseconds. The decay energy was determined to be 1690(17) keV, the 2p emission branching ratio is 37(14)%, and the half-life of 67Kr is 7.4(30) ms.

β decay of the very neutron-deficient Ge60 and Ge62 nuclei

We report here the results of a study of the $\beta$ decay of the proton-rich Ge isotopes, $^{60}$Ge and $^{62}$Ge, produced in an experiment at the RIKEN Nishina Center. We have improved our knowledge of the half-lives of $^{62}$Ge (73.5(1) ms), $^{60}$Ge (25.0(3) ms) and its daughter nucleus, $^{60}$Ga (69.4(2) ms). We measured individual $\beta$-delayed proton and $\gamma$ emissions and their related branching ratios. Decay schemes and absolute Fermi and Gamow-Teller transition strengths have been determined. The mass excesses of the nuclei under study have been deduced. A total $\beta$-delayed proton-emission branching ratio of 67(3)% has been obtained for $^{60}$Ge. New information has…

The $T_{z} = \pm 1 \to 0$ and $\pm 2 \to \pm 1$ Mirror Gamow--Teller Transitions in $pf$-shell Nuclei

Gamow–Teller (GT) transitions are the most common weak-interaction processes in the Universe. They play important roles in various processes of nucleosynthesis, for example, in the rapid proton-capture process (rp-process). In the pf-shell region, the rp-process runs through neutron-deficient nuclei with Tz = −2, −1, and 0 mainly by means of GT and Fermi transitions, where Tz is the z component of isospin T defined by Tz = (N − Z)∕2. Under the assumption of isospin symmetry, mirror nuclei with reversed Z and N numbers, and thus with opposite signs of Tz, have the same structure. Therefore, symmetry is also expected for the GT transitions starting from and ending up in mirror nuclei. We have…

TheNd150(He3,t) andSm150(t,He3) reactions with applications toββdecay ofNd150

The {sup 150}Nd({sup 3}He,t) reaction at 140 MeV/u and {sup 150}Sm(t,{sup 3}He) reaction at 115 MeV/u were measured, populating excited states in {sup 150}Pm. The transitions studied populate intermediate states of importance for the (neutrinoless) {beta}{beta} decay of {sup 150}Nd to {sup 150}Sm. Monopole and dipole contributions to the measured excitation-energy spectra were extracted by using multipole decomposition analyses. The experimental results were compared with theoretical calculations obtained within the framework of the quasiparticle random-phase approximation, which is one of the main methods employed for estimating the half-life of the neutrinoless {beta}{beta} decay (0{nu}{b…

High-resolution study of Gamow-Teller transitions in the47Ti(3He,t)47V reaction

In this work we have studied ${T}_{z}=+2\ensuremath{\rightarrow}+1$, Gamow-Teller (GT) transitions in the $^{48}\mathrm{Ti}(^{3}\mathrm{He},t)^{48}\mathrm{V}$ charge-exchange reaction at 140 MeV/nucleon and ${0}^{\ensuremath{\circ}}$ at the Research Center for Nuclear Physics, Osaka. From the high-resolution facility, consisting of a high-dispersion beamline and the Grand Raiden spectrometer, the spectrum had an energy resolution of 21 keV, among the best achieved. Individual GT transitions were observed and GT strength was derived for each state populated up to an excitation energy of 12 MeV. The total sum of the $B$(GT) strength observed in discrete states was 4.0, which is 33% of the sum…

High-resolution study of Gamow-Teller excitations in theCa42(He3,t)Sc42reaction and the observation of a “low-energy super-Gamow-Teller state”

Y. Fujita et al.; 15 pags.; 6 figs.; 7 tabs.; PACS number(s): 21.10.Hw, 25.55.Kr, 27.40.+z, 25.40.Ep

βDelayed γRay spectroscopy of heavy neutron rich nuclei “south” of lead

Relativistic projectile fragmentation of a 208Pb primary beam has been used to produce neutron-rich nuclei with proton-holes relative to the Z = 82 shell closure, i.e., “south” of Pb. βDelayed γRay spectroscopy allows to investigate the structural properties of such nuclei with A ~ 195 → 205. The current work presents transitions de-exciting excited states in 204Au, which are the first spectroscopic information on this N = 125 isotone. Agramunt Ros, Jorge, Jorge.Agramunt@ific.uv.es ; Algora, Alejandro, Alejandro.Algora@ific.uv.es ; Molina Palacios, Francisco Manuel, Francisco.Molina@ific.uv.es ; Rubio Barroso, Berta, Berta.Rubio@ific.uv.es

Simultaneous investigation of the T=1(Jπ=0+) and T=0(Jπ=9+) β decays in Br70

The $\beta$ decay of the odd-odd nucleus $^{70}$Br has been investigated with the BigRIPS and EURICA setups at the Radioactive Ion Beam Factory (RIBF) of the RIKEN Nishina Center. The $T=0$ ($J^{\pi}=9^+$) and $T=1$ ($J^{\pi}=0^+$) isomers have both been produced in in-flight fragmentation of $^{78}$Kr with ratios of 41.6(8)\% and 58.4(8)\%, respectively. A half-life of $t_{1/2}=2157^{+53}_{-49}$ ms has been measured for the $J^{\pi}=9^+$ isomer from $\gamma$-ray time decay analysis. Based on this result, we provide a new value of the half-life for the $J^{\pi}=0^+$ ground state of $^{70}$Br, $t_{1/2}=78.42\pm0.51$ ms, which is slightly more precise, and in excellent agreement, with the bes…

Sensitivity of the Cherenkov Telescope Array to a dark matter signal from the Galactic centre

Full list of authors: Acharyya, A.; Adam, R.; Adams, C.; Agudo, I.; Aguirre-Santaella, A.; Alfaro, R.; Alfaro, J.; Alispach, C.; Aloisio, R.; Alves Batista, R.; Amati, L.; Ambrosi, G.; Angüner, E. O.; Antonelli, L. A.; Aramo, C.; Araudo, A.; Armstrong, T.; Arqueros, F.; Asano, K.; Ascasíbar, Y. Ashley, M.; Balazs, C.; Ballester, O.; Baquero Larriva, A.; Barbosa Martins, V.; Barkov, M.; Barres de Almeida, U.; Barrio, J. A.; Bastieri, D.; Becerra, J.; Beck, G.; Becker Tjus, J.; Benbow, W.; Benito, M.; Berge, D.; Bernardini, E.; Bernlöhr, K.; Berti, A.; Bertucci, B.; Beshley, V.; Biasuzzi, B.; Biland, A.; Bissaldi, E.; Biteau, J.; Blanch, O.; Blazek, J.; Bocchino, F.; Boisson, C.; Bonneau Arbe…

Comparison of T[sub z] = ±1→0 GT Transitions Studied in β—decay and CE Reactions

Gamow‐Teller (GT) transitions can be studied in both β‐ decay and charge exchange(CE) reactions. If isospin is a good quantum number, then the Tz = −1→0 and Tz = +1→0 GT mirror transitions, are identical. Therefore, a comparison of the results from studies of β decay and CE should shed light on this assumption. Accordingly we have studied the β decay of the Tz = −1 fp‐shell nuclei, 54Ni, 50Fe, 46Cr, and 42Ti, produced in fragmentation and we have compared our results with the spectra from (3He, t) measurements on the mirror Tz = +1 target nuclei studied in high resolution at RCNP, Osaka. The experiments were performed as part of the STOPPED beam RISING campaign at GSI.

The T[sub z] = −1→ T[sub z] =0 beta decays and comparison with Charge Exchange reactions

Gamow‐Teller (GT) transitions can be studied in both β decay and charge exchange (CE) reactions. If isospin is a good quantum number, then the Tz = −1→0 and Tz = +1→0 GT mirror transitions, are identical. Therefore, a comparison of the results from studies of β decay and CE should shed light on this assumption. Accordingly we have studied the β decay of the Tz = −1 fp‐shell nuclei, 54Ni, 50Fe, 46Cr, and 42Ti, produced in fragmentation and we have compared our results with the spectra from (3He, t) measurements on the mirror Tz = +1 target nuclei studied in high resolution at RCNP, Osaka. The β decay experiments were performed as part of the STOPPED beam RISING campaign at GSI.

Gamow-Teller Transitions and β-decay Half-life in Proton Rich pf-shell Nuclei

In violent neutrino‐induced reactions at the core‐collapse stage of type II supernovae, Gamow‐Teller (GT) transitions starting from stable as well as unstable pf‐shell nuclei play important roles. In the β‐decay study of these unstable pf‐shell nuclei, half‐lives can be measured rather accurately. On the other hand, in high‐resolution (3He,t) charge‐exchange reactions at 0°, individual GT transitions up to high excitations can be studied. Assuming the isospin symmetry for the strengths of Tz = ±2→±1 analogous GT transitions, we present a “merged analysis” for the determination of GT transition strengths starting from proton‐rich Tz = −2 nuclei. We applied this analysis to the A = 52, T = 2 …

Gamow-Teller transitions in theA=40isoquintet of relevance for neutrino captures inAr40

Background: The Gamow-Teller response of $^{40}\mathrm{Ar}$ is important for the use of liquid argon as a medium for neutrino detection. An ambiguity about the Gamow-Teller strength for the excitation of ${1}^{+}$ states at 2290 and 2730 keV in $^{40}\mathrm{K}$ results in a significant uncertainty for neutrino capture rates. This ambiguity is caused by the large discrepancy observed between strengths extracted from $^{40}\mathrm{Ar}$($p$, $n$) charge-exchange data and the transition strengths for the analog transitions studied in the $\ensuremath{\beta}$ decay of $^{40}\mathrm{Ti}$.Purpose: This study was aimed at resolving the ambiguity between the results from the $^{40}\mathrm{Ar}$($p$,…

Observation of theβ-Delayedγ-Proton Decay ofZn56and its Impact on the Gamow-Teller Strength Evaluation

We report the observation of a very exotic decay mode at the proton drip line, the $\ensuremath{\beta}$-delayed $\ensuremath{\gamma}$-proton decay, clearly seen in the $\ensuremath{\beta}$ decay of the ${T}_{z}=\ensuremath{-}2$ nucleus $^{56}\mathrm{Zn}$. Three $\ensuremath{\gamma}$-proton sequences have been observed after the $\ensuremath{\beta}$ decay. Here this decay mode, already observed in the $sd$ shell, is seen for the first time in the $fp$ shell. Both $\ensuremath{\gamma}$ and proton decays have been taken into account in the estimation of the Fermi and Gamow-Teller strengths. Evidence for fragmentation of the Fermi strength due to strong isospin mixing is found.

Observation of the beta-Delayed gamma-Proton Decay of Zn-56 and its Impact on the Gamow-Teller Strength Evaluation

We report the observation of a very exotic decay mode at the proton drip line, the beta-delayed gamma-proton decay, clearly seen in the beta decay of the T-z = -2 nucleus Zn-56. Three gamma-proton sequences have been observed after the beta decay. Here this decay mode, already observed in the sd shell, is seen for the first time in the f p shell. Both. and proton decays have been taken into account in the estimation of the Fermi and Gamow-Teller strengths. Evidence for fragmentation of the Fermi strength due to strong isospin mixing is found.

The $^{150}$Nd($^3$He,$t$) and $^{150}$Sm($t$,$^3$He) reactions with applications to $\beta\beta$ decay of $^{150}$Nd

The $^{150}$Nd($^3$He,$t$) reaction at 140 MeV/u and $^{150}$Sm($t$,$^3$He) reaction at 115 MeV/u were measured, populating excited states in $^{150}$Pm. The transitions studied populate intermediate states of importance for the (neutrinoless) $\beta\beta$ decay of $^{150}$Nd to $^{150}$Sm. Monopole and dipole contributions to the measured excitation-energy spectra were extracted by using multipole decomposition analyses. The experimental results were compared with theoretical calculations obtained within the framework of Quasiparticle Random-Phase Approximation (QRPA), which is one of the main methods employed for estimating the half-life of the neutrinoless $\beta\beta$ decay ($0\nu\beta\…

Pygmy dipole resonance in Pb-208

Scattering of protons of several hundred MeV is a promising new spectroscopic tool for the study of electric dipole strength in nuclei. A case study of 208Pb shows that at very forward angles Jˇ = 1− states are strongly populated via Coulomb excitation. A separation from nuclear excitation of other modes is achieved by a multipole decomposition analysis of the experimental cross sections based on theoretical angular distributions calculated within the quasiparticle-phonon model. The B(E1) transition strength distribution is extracted for excitation energies up to 9 MeV, i.e., in the region of the so-called pygmy dipole resonance (PDR). The Coulomb-nuclear interference shows sensitivity to t…

Tz = ±1 → 0 ISOSPIN SYMMETRY GAMOW-TELLER TRANSITIONS IN pf-SHELL NUCLEI

Studying the Gamow-Teller (GT) transitions of stable as well as unstable pf-shell nuclei is one of the key issues in nuclear and astro-nuclear physics. Under the assumption that isospin T is a good quantum number, symmetry is expected for mirror nuclei and the GT transitions starting from the mirror nuclei. We study the GT transitions starting from Tz = ±1 mirror nuclei, respectively, by means of hadronic (3 He , t) charge-exchange reactions and complementary β decays.

Beta Decay Study of the Tz=−2 56Zn Nucleus and the Determination of the Half-Lives of a Few fp-shell Nuclei

Abstract This paper concerns the experimental study of the β decay properties of few proton-rich fp -shell nuclei. The nuclei were produced at GANIL in fragmentation reactions, separated with the LISE spectrometer and stopped in an implantation detector surrounded by Ge detectors. The β -delayed gammas, β -delayed protons and the exotic β -delayed gamma-proton emission have been studied. Preliminary results are presented. The decay of the T z = − 2 nucleus 56 Zn has been studied in detail. Information from the β -delayed protons and β -delayed gammas has been used to deduce the decay scheme. The exotic beta-delayed gamma-proton decay has been observed for the first time in the fp -shell. Th…

Gamow-Teller Transitions in Proton Rich Exotic pf-shell Nuclei Deduced from Mirror Transitions

The rp‐process nucleosynthesis proceeds through nuclei near the proton drip‐line, in which Gamow‐Teller (GT) transitions starting from unstable pf‐shell nuclei play important roles. In the β‐decay study of these nuclei, half‐lives can be measured rather accurately. On the other hand, in the high‐resolution (3He, t) charge‐exchange reactions on mirror nuclei, individual GT transitions can be studied up to high excitations. For the accurate study of the GT transition strengths in the A = 52, T = 2, system, we compare and combine the β‐decay study of the proton‐rich nucleus 52Ni and the 52Cr(3He, t) measurement assuming the isospin symmetry of the Tz = ±2→±1 transitions.