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In order to study the Gamow-Teller (GT) transitions from the T z=+2 nucleus 44Ca to the Tz=+1 nucleus 44Sc, where T z is the z component of isospin T, we performed the (p,n)-type (3He,t) charge-exchange (CE) reaction at 140 MeV/nucleon and the scattering angles 0â̂̃ and 2.5â̂̃. An energy resolution of 28 keV, that was realized by applying matching techniques to the magnetic spectrometer system, allowed the study of fragmented states. The GT transition strengths, B(GT), were derived up to the excitation energy (Ex) of 13.7 MeV assuming the proportionality between cross sections and B(GT) values. The total sum of B(GT) values in discrete states was 3.7, which was 31% of the sum-rule-limit value of 12. Shell model calculations using the GXPF1J interaction could reproduce the gross features of the experimental B(GT) distribution, but not the fragmentation of the strength. By introducing the concepts of isospin, properties of isospin analogous transitions and states were investigated. (i) Assuming isospin symmetry, the Tz=+2→+1 and Tz=-2→-1 mirror GT transitions should have the same properties, where the latter can be studied in the β decay of 44Cr to 44V. First, we confirmed that the β-decay half-life T1/2 of 44Cr can be reproduced using the B(GT) distribution from the 44Ca(3He,t) measurement. Then, the 0â̂̃, (3He,t) spectrum was modified to deduce the "β-decay spectrum" and it was compared with the delayed-proton spectrum from the 44Cr β decay. The two spectra were mostly in agreement for the GT excitations, but suppression of the proton decay was found for the T=2 isobaric analog state (IAS). (ii) Starting from the T=2 ground state of 44Ca, the (3He,t) can excite GT states (state populated by GT transitions) with T=1, 2, and 3. On the other hand, the 44Ca(p,p ′) reaction can excite spin-M1 states (states populated by spin-M1 transitions) with T=2 and 3 that are analogous to the T=2 and 3 GT states, respectively. By comparing the spectra from these two reactions, a T value of 2 is suggested for several GT states in the Ex=11.5-13.7 MeV region. (iii) It has been suggested that the T=2, Jπ=0+ double isobaric analog state (DIAS) at 9.338 MeV in the Tz=0 nucleus 44Ti forms an isospin-mixed doublet with a subsidiary 0+ state at 9.298 MeV. Since no corresponding state was found in the Tz=+1 nucleus 44Sc, we suggest T=0 for the subsidiary state. © 2013 American Physical Society. ispartof: Physical Review C, Nuclear Physics vol:88 issue:1 status: published

Given the importance of Gamow-Teller (GT) transitions in nuclear structure and astrophysical nuclear processes, we have studied T z =+ 3 / 2 →+ 1 / 2, GT transitions starting from the 47 Ti nucleus in the ( 3 He ,t ) charge-exchange reaction at 0 ◦ and at an intermediate incident energy of 140 MeV / nucleon. The experiments were carried out at the Research Center for Nuclear Physics (RCNP), Osaka, using the high-resolution facility with a high-dispersion beam line and the Grand-Raiden spectrometer. With an energy resolution of 20 keV, individual GT transitions were observed and GT strength was derived for each state populated up to an excitation energy ( E x ) of 12.5 MeV. The GT strength was widely distributed from low excitation energy up to 12.5 MeV, where we had to stop the analysis because of the high level density. The distribution of the GT strengths was compared with the results of shell model calculations using the GXPF1 interaction. The calculations could reproduce the experimental GT distributions well. The GT transitions from the ground state of 47 Ti and the M 1 transitions from the isobaric analog state in 47 V to the same low-lying states in 47 V are analogous. It was found that the ratios of GT transition strengths to the ground state, the 0.088-MeV state, and the 0.146-MeV state are similar to the ratios of the strengths of the analogous M 1 transitions from the isobaric analog state (IAS) to these states. The measured distribution of the GT strengths was also compared with those starting from the T z =+ 3 / 2 nucleus 41 Ktothe T z =+ 1 / 2 nucleus 41 Ca. ispartof: Physical Review C, Nuclear Physics vol:87 issue:1 pages:1-12 status: published

In order to study the Gamow-Teller (GT) transitions from the Tz=+2 nucleus 44Ca to the Tz=+1 nucleus 44Sc, where Tz is the z component of isospin T, we performed the (p,n)-type (3He,t) charge-exchange (CE) reaction at 140 MeV/nucleon and the scattering angles 0∘ and 2.5∘. An energy resolution of 28 keV, that was realized by applying matching techniques to the magnetic spectrometer system, allowed the study of fragmented states. The GT transition strengths, B(GT), were derived up to the excitation energy (Ex) of 13.7 MeV assuming the proportionality between cross sections and B(GT) values. The total sum of B(GT) values in discrete states was 3.7, which was 31% of the sum-rule-limit value of 12. Shell model calculations using the GXPF1J interaction could reproduce the gross features of the experimental B(GT) distribution, but not the fragmentation of the strength. By introducing the concepts of isospin, properties of isospin analogous transitions and states were investigated. (i) Assuming isospin symmetry, the Tz=+2→+1 and Tz=-2→-1 mirror GT transitions should have the same properties, where the latter can be studied in the β decay of 44Cr to 44V. First, we confirmed that the β-decay half-life T1/2 of 44Cr can be reproduced using the B(GT) distribution from the 44Ca(3He,t) measurement. Then, the 0∘, (3He,t) spectrum was modified to deduce the "β-decay spectrum" and it was compared with the delayed-proton spectrum from the 44Cr β decay. The two spectra were mostly in agreement for the GT excitations, but suppression of the proton decay was found for the T=2 isobaric analog state (IAS). (ii) Starting from the T=2 ground state of 44Ca, the (3He,t) can excite GT states (state populated by GT transitions) with T=1, 2, and 3. On the other hand, the 44Ca(p,p') reaction can excite spin-M1 states (states populated by spin-M1 transitions) with T=2 and 3 that are analogous to the T=2 and 3 GT states, respectively. By comparing the spectra from these two reactions, a T value of 2 is suggested for several GT states in the Ex=11.5-13.7 MeV region. (iii) It has been suggested that the T=2, Jπ=0+ double isobaric analog state (DIAS) at 9.338 MeV in the Tz=0 nucleus 44Ti forms an isospin-mixed doublet with a subsidiary 0+ state at 9.298 MeV. Since no corresponding state was found in the Tz=+1 nucleus 44Sc, we suggest T=0 for the subsidiary state.

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 Pb-208 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 9MeV; that is, in the region of the so-called pygmy dipole resonance (PDR). The Coulomb-nuclear interference shows sensitivity to the underlying structure of the E1 transitions, which allows for the first time an experimental extraction of the electromagnetic transition strength and the energy centroid of the PDR.

In order to study the Gamow-Teller (GT) transitions from the T z =+ 2 nucleus 44 Ca to the T z =+ 1 nucleus 44 Sc, where T z is the z component of isospin T , we performed the ( p, n )-type ( 3 He ,t ) charge-exchange (CE) reaction at 140 MeV / nucleon and the scattering angles 0 ◦ and 2 . 5 ◦ . An energy resolution of 28 keV, that was realized by applying matching techniques to the magnetic spectrometer system, allowed the study of fragmented states. The GT transition strengths, B (GT), were derived up to the excitation energy ( E x ) of 13.7 MeV assuming the proportionality between cross sections and B (GT) values. The total sum of B (GT) values in discrete states was 3.7, which was 31% of the sum-rule-limit value of 12. Shell model calculations using the GXPF1J interaction could reproduce the gross features of the experimental B (GT) distribution, but not the fragmentation of the strength. By introducing the concepts of isospin, properties of isospin analogous transitions and states were investigated. (i) Assuming isospin symmetry, the T z =+ 2 →+ 1and T z =− 2 →− 1 mirror GT transitions should have the same properties, where the latter can be studied in the β decay of 44 Cr to 44 V. First, we confirmed that the β -decay half-life T 1 / 2 of 44 Cr can be reproduced using the B (GT) distribution from the 44 Ca( 3 He ,t ) measurement. Then, the 0 ◦ ,( 3 He ,t ) spectrum was modified to deduce the “ β -decay spectrum” and it was compared with the delayed-proton spectrum from the 44 Cr β decay. The two spectra were mostly in agreement for the GT excitations, but suppression of the proton decay was found for the T = 2 isobaric analog state (IAS). (ii) Starting from the T = 2 ground state of 44 Ca, the ( 3 He ,t ) can excite GT states (state populated by GT transitions) with T = 1, 2, and 3. On the other hand, the 44 Ca( p, p ) reaction can excite spin- M 1 states (states populated by spin- M 1 transitions) with T = 2 and 3 that are analogous to the T = 2 and 3 GT states, respectively. By comparing the spectra from these two reactions, a T value of 2 is suggested for several GT states in the E x = 11 . 5–13.7 MeV region. (iii) It has been suggested that the T = 2, J π = 0 + double isobaric analog state (DIAS) at 9.338 MeV in the T z = 0 nucleus 44 Ti forms an isospin-mixed doublet with a subsidiary 0 + state at 9.298 MeV. Since no corresponding state was found in the T z =+ 1 nucleus 44 Sc, we suggest T = 0 for the subsidiary state. ispartof: Physical Review C, Nuclear Physics vol:85 issue:2 pages:1-15 status: published

The rise time of stellar x-ray bursts is a signature of thermonuclear runaway processes in the atmosphere of neutron stars and is highly sensitive to a series of (alpha, p) reactions via high-lying resonances in sd-shell nuclei. Lacking data for the relevant resonance levels, the stellar reaction rates have been calculated using statistical, Hauser-Feshbach models, assuming a high-level density. This assumption may not be correct in view of the selectivity of the (alpha, p) reaction to natural parity states. We measured the Si-28(p,t)Si-26 reaction with a high-resolution spectrometer to identify resonance levels in Si-26 above the alpha-emission threshold at 9.164 MeV excitation energy. These resonance levels are used to calculate the stellar reaction rate of the Mg-22(alpha,p)Al-25 reaction and to test the validity of the statistical assumption.

A benchmark experiment on Pb-208 shows that polarized proton inelastic scattering at very forward angles including 0 degrees is a powerful tool for high-resolution studies of electric dipole (E1) and spin magnetic dipole (M1) modes in nuclei over a broad excitation energy range to test up-to-date nuclear models. The extracted E1 polarizability leads to a neutron skin thickness r(skin) = 0.156(-0.021)(+0.025) fm in Pb-208 derived within a mean-field model [Phys. Rev. C 81, 051303 (2010)], thereby constraining the symmetry energy and its density dependence relevant to the description of neutron stars.

A high-energy-resolution Be-9(He-3,t)B-9 charge-exchange reaction was performed around a scattering angle of 0 degrees. and at an intermediate incident energy of 140 MeV/ nucleon for the study of precise Gamow-Teller (GT) transition strengths. The energy resolution of 30 keV allowed a precise deconvolution of the spectrum and the determination of angular distributions of cross sections, excitation energies, and decay widths. The GT strength of 10 states has been determined for the first time using the GT strength of the analogous beta decays of Li-9 and C-9 as standards. The large difference between the GT strengths going to the low-lying T = 1/ 2 and the highly excited T = 3/ 2 states is interpreted as a result of their different spatial structures. The obtained GT strength distribution is compared to the results of a (p, n) experiment with lower resolution performed in the 1980s. In particular, the width of the 16.8 MeV, J(pi) = (5/2(+)) state has been determined for the first time.

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 thus provide useful information on the neutrino responses for evaluating the 0 nu beta beta and 2 nu beta beta matrix elements. The 2 nu beta beta matrix element calculated from the Gamow-Teller transitions through the lowest 1(+) state in the intermediate nucleus is maximally about half that deduced from the half-life measured in 2 nu beta beta direct counting experiments, and at least several transitions through 1+ intermediate states in Pm-150 are required to explain the 2 nu beta beta half-life. Because Gamow-Teller transitions in the Sm-150(t,3He) experiment are strongly Pauli blocked, the extraction of Gamow-Teller strengths was complicated by the excitation of the 2 (h) over bar omega, Lambda L = 0, Delta S = 1 isovector spin-flip giant monopole resonance (IVSGMR). However, the near absence of Gamow-Teller transition strength made it possible to cleanly identify this resonance, and the strength observed is consistent with the full exhaustion of the non-energy-weighted sum rule for the IVSGMR.

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 thus provide useful information on the neutrino responses for evaluating the 0 nu beta beta and 2 nu beta beta matrix elements. The 2 nu beta beta matrix element calculated from the Gamow-Teller transitions through the lowest 1(+) state in the intermediate nucleus is maximally about half that deduced from the half-life measured in 2 nu beta beta direct counting experiments, and at least several transitions through 1+ intermediate states in Pm-150 are required to explain the 2 nu beta beta half-life. Because Gamow-Teller transitions in the Sm-150(t,3He) experiment are strongly Pauli blocked, the extraction of Gamow-Teller strengths was complicated by the excitation of the 2 (h) over bar omega, Lambda L = 0, Delta S = 1 isovector spin-flip giant monopole resonance (IVSGMR). However, the near absence of Gamow-Teller transition strength made it possible to cleanly identify this resonance, and the strength observed is consistent with the full exhaustion of the non-energy-weighted sum rule for the IVSGMR.

Since the identification of ongoing Al-26 production in the universe, the reaction sequence Mg-24(p,gamma)Al-25(beta(+)nu)Mg-25(p,gamma)Al-26 has been studied intensively. At temperatures where the radiative capture on Al-25 (t(1/2) = 7.2 s) becomes faster than the beta(+) decay, the production of Al-26 can be reduced due to the depletion of Al-25. To determine the resonances relevant for the Al-25(p,gamma) Si-26 bypass reaction, we measured the Si-28(p,t)Si-26 reaction with high-energy precision using the Grand Raiden spectrometer at the Research Center for Nuclear Physics, Osaka. Several new energy levels were found above the p threshold and for known states excitation energies were determined with smaller uncertainties. The calculated stellar rates of the bypass reaction agree well with previous results, suggesting that these rates are well established.

Since the identification of ongoing 26Al production in the universe, the reaction sequence 24Mg(p,γ )25Al(β+ν)25Mg(p,γ )26Al has been studied intensively. At temperatures where the radiative capture on 25Al (t1/2 = 7.2 s) becomes faster than the β+ decay, the production of 26Al can be reduced due to the depletion of 25Al. To determine the resonances relevant for the 25Al(p,γ )26Si bypass reaction, we measured the 28Si(p,t )26Si reaction with high-energy precision using the Grand Raiden spectrometer at the Research Center for Nuclear Physics, Osaka. Several new energy levels were found above the p threshold and for known states excitation energies were determined with smaller uncertainties. The calculated stellar rates of the bypass reaction agree well with previous results, suggesting that these rates are well established.

On March 23, 2009, the first beam was successfullytransported to the final focal plane of the SHARAQspectrometer. We investigated detector responses toheavy-ion beams and the ion optical properties ofthe SHARAQ spectrometer1) and the high-resolutionbeam line2) in the subsequent commissioning runs andfound that the system as a whole worked almost as perits design. The first physics run with the spectrometerwas performed in November 2009. In this article, wereview the progress in the SHARAQ project in 2009.

x-ray bursts are identified as thermonuclear explosions in the outer atmosphere of accreting neutron stars. The thermonuclear runaway is fueled by the alpha p process that describes a sequence of (alpha,p) reactions triggered by the Ne-18(alpha,p)Na-21 breakout reaction from the hot CNO cycles. We studied the level structure of the compound nucleus Mg-22 by measuring the Mg-24(p,t)Mg-22 reaction at the Grand Raiden spectrometer at Research Center for Nuclear Physics, Osaka. A large number of alpha-unbound states was identified and precise excitation energies were determined. Based on shell model and alpha-cluster model calculations we predict the level parameters for determining the stellar reaction rate of Ne-18(alpha,p)Na-21 for a wide temperature range. x-ray burst simulations have been performed to study the impact of the reaction on the x-ray burst luminosity.

To study the Gamow-Teller (GT) transitions to the pf-shell nucleus Cu-64, the Ni-64(He-3,t)Cu-64 experiment was performed at the Research Center for Nuclear Physics (RCNP) Ring Cyclotron, Osaka, using a He-3 beam of 140 MeV/nucleon. The outgoing tritons were momentum analyzed by the Grand Raiden spectrometer at 0(degrees). A high energy resolution of 32 keV (full width at half-maximum) allowed the separation of individual levels in the excitation-energy region from 0 to 3.5 MeV. In addition to the ground state (gs), known to be a J(pi)=1(+) GT state, many low-lying states showed L=0 nature, suggesting that they are candidates for GT states. Because the GT strength B(GT) for the gs transition is known from the beta-decay measurement, the strengths for the excited states could be determined using the proportionality between the B(GT) and the reaction cross section extrapolated to q=0 momentum transfer. At higher excitation energies, the level density becomes high and the so-called GT giant resonance dominates the spectrum. The lower and the upper limits of the strength contained in this energy region were estimated. Our results show that less than 55% of the strength predicted by the Ikeda sum rule is located in the excitation-energy region from 0 to 17 MeV..

x-ray bursts are identified as thermonuclear explosions in the outer atmosphere of accreting neutron stars. The thermonuclear runaway is fueled by the alphap process that describes a sequence of (alpha,p) reactions triggered by the 18Ne(alpha,p)21Na breakout reaction from the hot CNO cycles. We studied the level structure of the compound nucleus 22Mg by measuring the 24Mg(p,t)22Mg reaction at the Grand Raiden spectrometer at Research Center for Nuclear Physics, Osaka. A large number of alpha-unbound states was identified and precise excitation energies were determined. Based on shell model and alpha-cluster model calculations we predict the level parameters for determining the stellar reaction rate of 18Ne(alpha,p)21Na for a wide temperature range. x-ray burst simulations have been performed to study the impact of the reaction on the x-ray burst luminosity.

In-beam gamma-ray spectroscopy of Fe-66,Fe-68 following intermediate-energy one- and two-proton knockout from cobalt and nickel secondary beams has been performed at the National Superconducting Cyclotron Laboratory. New transitions have been observed in Fe-66 and Fe-68. This is the first observation of gamma-ray transitions in Fe-68. In addition, Cr-64 was produced using the Be-9(Fe-66,Cr-64)X two-proton knockout reaction. An unexpectedly low inclusive cross section is observed for this reaction, an order of magnitude smaller than for the Be-9(Ni-68,Fe-66)X reaction. This observation is discussed in terms of a significant structural difference between Fe-66 and Cr-64 and considerable admixtures of nu(pf)(n-2) (g(9/2))(+2) configurations in the ground and excited states of Cr-64 at N = 40.

Differential cross sections for transitions of known weak strength were measured with the (He-3, t) reaction at 420 MeV on targets of C-12, C-13, O-18, Mg-26, Ni-58, Ni-60, Zr-90, Sn-118, Sn-120, and Pb-208. Using these data, it is shown that the proportionalities between strengths and cross sections for this probe follow simple trends as a function of mass number. These trends can be used to confidently determine Gamow-Teller strength distributions in nuclei for which the proportionality cannot be calibrated via beta-decay strengths. Although theoretical calculations in the distorted-wave Born approximation overestimate the data, they allow one to understand the main experimental features and to predict deviations from the simple trends observed in some of the transitions.

Isospin is a good quantum number under the assumption that the nuclear interaction is charge independent. An analogous structure of excited states is expected for nuclei with the same mass number A but with different z components T_z of the isospin T, where T_z=(N-Z)/2. The analogous structure has been studied for the isobaric nuclei $^{58}$Ni and $^{58}$Cu by comparing the transitions from the $^{58}$Ni ground state (initial isospin T_i=1 and J^\pi=0^+) to the M1 and the Gamow-Teller (GT) states (J^\pi=1^+) in $^{58}$Ni and $^{58}$Cu, respectively. For this purpose, proton inelastic scattering (p,p') at E_p=160 MeV and the charge-exchange (^{3}He,t) reaction at 140 MeV/nucleon were both measured at 0°, exciting final states with isospin T_f=1 and 2 and T_f=0, 1, and 2, respectively. High energy and scattering-angle resolutions were achieved by applying complete beam matching techniques. On the basis of the correspondence between excitation energies and transition strengths, isospin values T_f=1 and 2 of analog GT and M1 states were identified. The distribution of T_f=2 states was also compared with results of $^{58}$Ni(d,^{2}He), $^{58}$Ni(t,^{3}He), and $^{58}$Ni(n,p) experiments, in which only T_f=2 states are excited. The obtained GT strength distribution is compared with the results of shell-model calculations.

It is shown via a study on a Mg-26 target that the (t,He-3) reaction at 115 MeV/nucleon reaction is an accurate probe for extracting Gamow-Teller transition strengths. To do so, the data are complemented by results from the Mg-26(He-3, t) reaction at 140 MeV/nucleon that allows for a comparison of T=2 analog states excited via the mirror reactions. Extracted Gamow-Teller strengths from Mg-26(t,He-3) and Mg-26(He-3, t) are compared with those from Mg-26(d,He-2) and Mg-26(p,n) studies, respectively. A good correspondence is found, indicating probe independence of the strength extraction. Furthermore, we test shell-model calculations using the new USD-05B interaction in the sd-model space and show that it reproduces the experimental Gamow-Teller strength distributions well. In anticipation of further (t,He-3) experiments on medium-heavy nuclei aimed at determining weak-interaction rates of relevance for stellar evolution, a second goal of this work is to improve the understanding of the (t,He-3) and (He-3, t) reaction mechanisms at intermediate energies because detailed studies are scarce. The distorted-wave Born approximation is employed, taking into account the composite structures of the He-3 and triton particles. The reaction model provides the means to explain systematic uncertainties at the 10%-20% level in the extraction of Gamow-Teller strengths as being because of interference between Gamow-Teller Delta L=0,Delta S=1 and Delta L=2,Delta S=1 amplitudes that both contribute to transitions from 0(+) to 1(+) states.

The Gamow-Teller (GT) transition strengths in fp -shell nuclei are important parameters in presupernova models. A high-energy-resolution ( 3 He ,t ) experiment was performed on the T z = 1 nucleus 46 Ti at 0 ◦ and at an intermediate incident energy of 140 MeV/nucleon for the study of precise GT transition strengths to the final T z = 0 nucleus 46 V. With an energy resolution of 33 keV, individual GT transitions were observed and GT strengths were derived for them up to the excitation energy of 4.5 MeV. The GT strengths were compared with shell-model calculations using various effective interactions. In this low-lying region, most GT states have isospin T = 0. A few GT states with isospin T = 1 were identified from the existence of the corresponding (analog) M 1 states in 46 Ti. By comparing the GT strength with the corresponding (analogous) M 1 transition strength studied in 46 Ti( e, e )or( γ,γ ) measurements, a large constructive interference of orbital and spin terms was suggested for one of these M 1 transitions ispartof: Physical Review C, Nuclear Physics vol:73 issue:2 status: published

In order to study the Gamow-Teller (GT) transitions in the fp-shell nucleus Cu-64, the Ni-64(He-3, t)Cu-64 charge-exchange reaction was investigated at E-3He 140 MeV/nucleon [1]. The outgoing tritons were momentum analysed by. the Grand Raiden spectrometer at 0 degrees. The very high energy resolution of 35 keV (FWHM) allowed the separation of individual levels in the excitation energy region from 0 to 3.5 MeV. An angular distribution analysis was performed for the observed transitions to these states. In addition to the ground state (g.s.), known to be a J(pi) = 1(+) GT state, several excited states showed L = 0 nature, making them candidates of GT states. At higher excitation energies, the level density becomes very high and a bump-like structure, the so-called GT Giant Resonance, dominates the spectrum.

A C-14(He-3,t)O-14 experiment was performed using a He-3 beam with E=140 MeV/nucleon. The achieved resolution of 33 keV (full width at half maximum) for the small scattering angle spectrum allowed the determination of the widths of several levels up to an excitation energy of 11.5 MeV. The width of the E-x=5.17 MeV,J(pi)=1(-) level was in good agreement with the known value, while for other states considerably improved or new results were obtained.

Under the assumption that isospin T is a good quantum number, isobaric analog states and various analogous transitions are expected in isobars with mass number A. The, strengths of T-z = +/-3/2 --> 1/2 analogous Gamow-Teller (GT) transitions and analogous M1 transitions within the A = 41 isobar quartet are compared in detail. The T-z = +3/2 --> +1/2 GT transitions from the J(pi) = 3/2(+) ground state of K-41 leading to excited J(pi) = 1/2(+), 3/2(+), and 5/2(+) states in Ca-41 were measured using the (He-3, t) charge-exchange reaction. With a high energy resolution of 35 keV, many fragmented states were observed, and the GT strength distribution was determined up to 10 MeV excitation energy (E-x). The main part of the strength was concentrated in the E-x = 4-6 MeV region. A shell-model calculation could reproduce the concentration, but not so well details of the strength distribution. The obtained distribution was further compared with two results of Ti-41 beta decay studying the analogous T-z = -3/2 --> -1/2 GT strengths. They reported contradicting distributions. One-to-one correspondences of analogous transitions and analog states were assigned up to E-x = 6 MeV in the comparison with one of these Ti-41 beta-decay results. Combining the spectroscopic information of the analog states in Ca-41 and Sc-41, the most probable J(pi) values were deduced for each pair of analog states. It was found that 5/2(+) states carry the main part of the observed GT strength, while much less GT strength was carried by 1/2(+) and 3/2(+) states. The gross features of the GT strength distributions for each J were similar for the isospin analogous T-z = +/-3/2 --> +/-1/2 transitions, but the details were somewhat different. From the difference of the distributions, isospin-asymmetry matrix elements of 8 keV were deduced. The Coulomb displacement energy, which is sensitive to the configuration of states, showed a sudden increase of about 50 keV at the excitation energy of 3.8 MeV. The strengths of several M1 transitions to the IAS in Ca-41 were compared with the strengths of analogous GT transitions. It was found that ratios of the M1 and GT transition strengths were similar, suggesting that the contributions of the ltau term in M1 transitions are small.

A high energy-resolution B-11 (He-3,t)C-11 experiment was performed at 0degrees and an intermediate incident energy of 140 MeV/nucleon for the study of precise Gamow-Teller (GT) transition strengths. Two doublet states at approximate to4.5 and approximate to8.4 MeV were clearly resolved with a resolution of 45 keV. The strengths are compared with a calculation using an ab initio no-core shell model, which became available for the A=11 system recently. It was found that a calculation including a three-nucleon interaction better reproduces the observed GT transition strengths.

After 50 years of its prediction, the highest-lying [2 0 2]3/2 orbit among the six Nilsson single-particle orbits originating from the sd shells in prolately deformed nuclei and the rotational band on this orbit were identified. The band members were observed in Al-25 at excitation energies of 6-7.5 MeV in a high-resolution Mg-25(He-3,t) charge-exchange reaction at 0degrees having a strong selectivity for Gamow-Teller transitions. In the comparison with the analogous M1 transitions in Mg-25, the J(pi)=3/2(+) bandhead state and the excited 5/2(+) and 7/2(+) members were clearly assigned.

Nuclei in the A similar to 180 region have been populated and investigated in a series of multinucleon transfer and deep-inelastic reactions involving an 11.4 MeV per nucleon Xe-136 beam produced by the GSI UNILAC accelerator, impinging on a selection of tantalum and tungsten targets. The reaction products were released from a thermal ion source and subsequently mass selected using the GSI on-line mass separator. The unexpectedly high yield of gamma rays associated with the decay of the well established K-pi=37/2(-),t(1/2)=51.4 min isomer in Hf-177(72) and anomalous half-life characteristics associated with this decay lead to these data being interpreted as the beta(-) decay of a high-K isomer in the mother nucleus, Lu-177. By comparing the experimental findings with the predictions obtained from multi-quasiparticle blocked-BCS-Nilsson calculations, the proposed decay is suggested to be from a K-pi=39/2(-) five-quasiparticle state in Lu-177(71). A half-life of 7 +/- 2 min is determined for this beta-decay path which is estimated to have an excitation energy of approximate to3.9 MeV above the Lu-177 ground state.

Under the assumption that isospin is a good quantum number, symmetry is expected for the transitions from the ground states of T = 1, T-z = +/-1 nuclei to the common excited states of the T-z = 0 nucleus situated between the two nuclei. The symmetry can be studied by comparing the strengths of Gamow-Teller (GT) transitions obtained from a (p, n)-type charge-exchange reaction on a target nucleus with T-z = 1 with those from the beta-decay of the T-z = -1 nucleus. The A = 58 system is the heaviest for which such a comparison is possible. As a part of the symmetry study, we measured the GT transitions from Ni-58 (T-z = 1) to Cu-58 (T-z = 0) by using the zero-degree (He-3,t) reaction at 150 MeV/nucleon. With the achieved resolution of 50 keV, many hitherto unresolved GT states have been identified. The GT transition strengths were obtained for states up to 8 MeV excitation, i.e., Dear to the Q window limitation (Q(EC) = 9.37 MeV) of the beta-decay from Zn-58 (T-z = -1) to Cu-58. The strength distribution is compared with that from shell-model calculations.