The Gamow-Teller strength distribution covering the entire beta-decay window, up to 10.312(4) MeV, of 80g+mGa was measured for the first time in photofission of UCx induced by a 50 MeV electron beam. The new data show significant enhancement in the high-energy region with a jump structure. Simultaneously, the gamma deexciting behavior of beta-populated states presents a competition between deexcitation to 2+1 [beta 2 = 0.155(9)] and to 2+2 [beta 2 = 0.0530.008 0.009)] in 80Ge. To understand these data, we performed a realistic shell-model calculation and systematic analysis of log ft ratios between precursors' beta decay to 2+2 and to 2+1 of Ga isotopes. We conclude that these phenomena evidence simultaneous impacts of nuclear shell structure and collectivity on B(GT) distribution and therefore the half-life of the precursor.

Missing mass spectroscopy of the unbound C-8 nucleus was performed by the one-neutron transfer 9C(p,d)8C reaction at 55 MeV/nucleon. Besides the known ground state, two new resonant states were observed, the first at an excitation energy of 3.40(25) MeV with a width of 3.0(5) MeV, the second at 18.6(5) MeV with a width of 3.9(11) MeV. Spin and parity J(pi)=2(+) were assigned to the first resonance from the distorted-wave Born approximation analysis of the experimental differential cross section. The excitation energy of the 2(+) resonance in C-8 supports the persistence of the subshell closure at the semimagic number Z = 6, as is the case for N = 6. The mirror energy difference relative to the 2(+ )state in 8He, Delta E-x=-0.14(25) MeV, is compatible with zero. Both states represent resonances in the continuum, unbound by about 1.4 and 6.9 MeV, respectively, above the particle thresholds. A simple theoretical model emphasizes the difference in unboundedness to account for a symmetry in mirror energies. This unique system is expected to provide a salient test of theoretical models, which include the treatment of the continuum.

Missing mass spectroscopy of the unbound $^{8}\mathrm{C}$ nucleus was performed by the one-neutron transfer $^{9}\mathrm{C}(p,d)^{8}\mathrm{C}$ reaction at 55 MeV/nucleon. Besides the known ground state, two new resonant states were observed, the first at an excitation energy of 3.40(25) MeV with a width of 3.0(5) MeV, the second at 18.6(5) MeV with a width of 3.9(11) MeV. Spin and parity ${J}^{\ensuremath{\pi}}={2}^{+}$ were assigned to the first resonance from the distorted-wave Born approximation analysis of the experimental differential cross section. The excitation energy of the ${2}^{+}$ resonance in $^{8}\mathrm{C}$ supports the persistence of the subshell closure at the semimagic number $Z$ = 6, as is the case for $N$ = 6. The mirror energy difference relative to the ${2}^{+}$ state in $^{8}\mathrm{He}, \mathrm{\ensuremath{\Delta}}{E}_{\mathrm{x}}=\ensuremath{-}0.14$(25) MeV, is compatible with zero. Both states represent resonances in the continuum, unbound by about 1.4 and 6.9 MeV, respectively, above the particle thresholds. A simple theoretical model emphasizes the difference in unboundedness to account for a symmetry in mirror energies. This unique system is expected to provide a salient test of theoretical models, which include the treatment of the continuum.

A new β-decay station, COnversion electrons Chasing at Orsay (COeCO), has been developed at ALTO to perform conversion electron spectroscopy studies of neutron-rich nuclei produced by photo-fission of a uranium carbide target. It is based on the collection of a low-energy ISOL beam on a mylar tape, and the transportation of the electrons emitted by the produced radioactive source through a magnetic field induced by two copper coils, towards a cooled Si(Li) detector. In this article, a detailed description of the new decay station and its components is given. The magnetic field induced by the coils was measured and compared to simulations performed with the COMSOL® software. The efficiency of the detection setup was estimated using a 207Bi and a 152Eu source as an off-line commissioning. Finally, the results obtained with a 96Rb radioactive beam for the on-line commissioning are presented.

Abstract We predict the existence of medium spin PDR and find experimental evidence in 80Ge using β-decay of 80Ga. This nucleus was produced in the photo-fission of 238U. A hybrid γ-ray spectrometer was developed using a plastic detector for β-tagging, HPGe detectors for low-energy γ rays detection and phoswich detectors of PARIS for high-energy γ rays. The low-high energy coincidence spectrum shows two peaks at 7181(53) and 7337(53) keV in the β-decay of the 80mGa isomeric state only, in coincidence with the 21+ → 0+ transition of 80Ge. Combined with decay information, electric dipole character (E1) were assigned to these γ rays which de-excite 7.84 MeV and 7.996 MeV states. Based on this fact and the comparison with theoretical calculations, we conclude that these enhanced E1 transitions are driven by neutron-skin oscillation of 80Ge. The oscillation is triggered by a conversion of a deeply-bound neutron from the Z=N=28 proton-neutron saturated core into a proton in the Fermi surface. These results provide an evidence for a PDR state with spin different from 1− and built on a low-energy excited state. Consequently, it extends the PDR’s boundary along spin dimension for the first time and provides experimental data for testing the validity of the Brink-Axel hypothesis in the PDR region.

The last proton bound calcium isotope 35Ca has been studied for the first time, using the 37Ca(p; t)35Ca two neutron transfer reaction. The radioactive 37Ca nuclei, produced by the LISE spectrometer at GANIL, interacted with the protons of the liquid hydrogen target CRYPTA, to produce tritons t that were detected in the MUST2 detector array, in coincidence with the heavy residues Ca or Ar. The atomic mass of 35Ca and the energy of its first 3/2+ state are reported. A large N = 16 gap of 4.61(11) MeV is deduced from the mass measurement, which together with other measured properties, makes 36Ca a doubly magic nucleus. The N = 16 shell gaps in 36Ca and 24O are of similar amplitude, at both edges of the valley of stability. This feature is discussed in terms of nuclear forces involved, within state-of-the-art shell model calculations. Even though the global agreement with data is quite convincing, the calculations underestimate the size of the N = 16 gap in 36Ca by 840 keV.

Excited states in the N = 50 nucleus Ge-82 have been investigated via beta decay of Ga-82 at the ALTO facility. More than 50 new gamma transitions were identified. The preliminary results are presented in this work.

The isovector and isoscalar components of neutron-proton pairing are investigated in the N=Z unstable nuclei of the fp-shell through the two-nucleon transfer reaction (p,3He) in inverse kinematics. The combination of particle and gamma-ray detection with radioactive beams of 56Ni and 52Fe, produced by fragmentation at the GANIL/LISE facility, made it possible to carry out this study for the first time in a closed and an open-shell nucleus in the fp-shell. The transfer cross-sections for ground-state to ground-state (J=0,T=1) and to the first (J=1,T=0) state were extracted for both cases together with the transfer cross-section ratios σ(0,T=1) /σ(1,T=0). They are compared with second-order distorted-wave born approximation (DWBA) calculations. The enhancement of the ground-state to ground-state pair transfer cross-section close to mid-shell, in 52Fe, points towards a superfluid phase in the isovector channel. For the ”deuteron-like” transfer, very low cross-sections to the first (J=1,T=0) state were observed both for 56Ni(p,3He) and 52Fe(p,3He) and are related to a strong hindrance of this channel due to spin-orbit effect. No evidence for an isoscalar deuteron-like condensate is observed.

Neutron transfer reaction measurements, relevant to the neutrinoless double beta decay candidate 124Sn and its daughter 124Te, have been performed. Precise measurements of both neutron addition [(d, p), (4He, 3He)] and removal [(p, d), (3He, 4He)] cross sections have been used to determine the occupation of valence orbitals pertinent to neutrinoless double beta decay in these two nuclei. This information could be used to constrain calculations of the nuclear matrix element for the neutrinoless double beta decay of 124Sn. The change in the ground-state neutron vacancies in proceeding from 124Sn to 124Te is mainly found in the d3/2,5/2 and h11/2 orbitals. The occupancies of states near the Fermi level are in reasonable agreement with shell model calculations.

Detailed spectroscopy of the neutron-deficient nucleus ^{36}Ca was obtained up to 9 MeV using the ^{37}Ca(p,d)^{36}Ca and the ^{38}Ca(p,t)^{36}Ca transfer reactions. The radioactive nuclei, produced by the LISE spectrometer at GANIL, interacted with the protons of the liquid hydrogen target CRYPTA, to produce light ejectiles (the deuteron d or triton t) that were detected in the MUST2 detector array, in coincidence with the heavy residues identified by a zero-degree detection system. Our main findings are (i) a similar shift in energy for the 1_{1}^{+} and 2_{1}^{+} states by about -250  keV, as compared with the mirror nucleus ^{36}S; (ii) the discovery of an intruder 0_{2}^{+} state at 2.83(13) MeV, which appears below the first 2^{+} state, in contradiction with the situation in ^{36}S; and (iii) a tentative 0_{3}^{+} state at 4.83(17) MeV, proposed to exhibit a bubble structure with two neutron vacancies in the 2s_{1/2} orbit. The inversion between the 0_{2}^{+} and 2_{1}^{+} states is due to the large mirror energy difference (MED) of -516(130)  keV for the former. This feature is reproduced by shell model calculations, using the sd-pf valence space, predicting an almost pure intruder nature for the 0_{2}^{+} state, with two protons (neutrons) being excited across the Z=20 magic closure in ^{36}Ca (^{36}S). This mirror system has the largest MEDs ever observed, if one excludes the few cases induced by the effect of the continuum.

The unbound proton-rich nuclei ^16 F and ^15 F are investigated experimentally and theoretically. Several experiments using the resonant elastic scattering method were performed at GANIL with radioactive beams to determine the properties of the low lying states of these nuclei. Strong asymmetry between ^16 F– ^16 N and ^15 F– ^15 C mirror nuclei is observed. The strength of the nucleon-nucleon effective interaction involving the loosely bound proton in the s_1/2 orbit is significantly modified with respect to their mirror nuclei ^16 N and ^15 C. The reduction of the effective interaction is estimated by calculating the interaction energies with a schematic zero-range force. It is found that, after correcting for the effects due to changes in the radial distribution of the single-particle wave functions, the mirror symmetry of the n-p interaction is preserved between ^16 F and ^16 N, while a difference of 63

Background: A recent sensitivity study has shown that the K-35(p, gamma) Ca-36 reaction is one of the ten (p, gamma) reaction rates that could significantly impact the shape of the calculated x-ray burst light curve. Its reaction rate used up to now in type I x-ray burst calculations was estimated using an old measurement for the mass of Ca-36 and theoretical predictions for the partial decay widths of the first 2(+) resonance with arbitrary uncertainties. Purpose: In this work, we propose to reinvestigate the K-35(p, gamma) Ca-36 reaction rate, as well as related uncertainties, by determining the energies and decay branching ratios of Ca-36 levels, within the Gamow window of x-ray bursts, in the 0.5 to 2 GK temperature range. Method: These properties were studied by means of the one-neutron pickup transfer reaction Ca-37(p, d) Ca-36 in inverse kinematics using a radioactive beam of Ca-37 at 48 MeV nucleon(-1). The experiment was performed at the GANIL facility using the liquid hydrogen target CRYPTA, the MUST2 charged particle detector array for the detection of the light charged particles, and a zero degree detection system for the outgoing heavy recoil nuclei. Results: The atomic mass of Ca-36 is confirmed and new resonances have been proposed together with their proton decay branching ratios. This spectroscopic information, used in combination with very recent theoretical predictions for the gamma-decay width, were used to calculate the K-35(p, gamma) Ca-36 reaction rate. The recommended rate of the present work was obtained within a uncertainty factor of 2 at 1 sigma. This is consistent with the previous estimate in the x-ray burst temperature range. A large increase of the reaction rate was found at higher temperatures due to two newly discovered resonances. Conclusions: The K-35(p, gamma) Ca-36 thermonuclear reaction rate is now well constrained by the present work in a broad range of temperatures covering those relevant to type I x-ray bursts. Our results show that the K-35(p, gamma) Ca-36 reaction does not affect the shape of the x-ray burst light curve, and that it can be removed from the list of the few influential proton radiative captures reactions having a strong impact on the light curve.

A recent sensitivity study has shown that the $^{35}$K$(p,\gamma)^{36}$Ca reaction is one of the ten $(p,\gamma)$ reaction rates that could significantly impact the shape of the calculated X-ray burst light curve. In this work, we propose to reinvestigate the $^{35}$K$(p,\gamma)^{36}$Ca reaction rate, as well as related uncertainties, by determining the energies and decay branching ratios of $^{36}$Ca levels, within the Gamow window, in the 0.5 to 2 GK X-ray burst temperature range. These properties were studied using the one neutron pick-up transfer reaction $^{37}$Ca$(p,d)^{36}$Ca in inverse kinematics using a radioactive beam of $^{37}$Ca at 48 MeV nucleon$^{-1}$. The experiment performed at GANIL, used the liquid Hydrogen target CRYPTA, the MUST2 detector array for the detection of the light charged particles and a zero degree detection system for the outgoing heavy ions. The atomic mass of $^{36}$Ca is confirmed and new resonances have been proposed together with their proton decay branching ratios. This spectroscopic information, used in combination with recent theoretical predictions for the $\gamma$-width, were used to calculate the $^{35}$K$(p,\gamma)^{36}$Ca reaction rate. The recommended rate of the present work was obtain within a uncertainty factor of 2 at 1 sigma. This is consistent, with the previous estimate in the X-ray burst temperature range. A large increase of the reaction rate was found at higher temperatures due to two newly discovered resonances. The $^{35}$K$(p,\gamma)^{36}$Ca thermonuclear reaction rate is now well constrained by the present work in a broad range of temperatures. Our results show that the $^{35}$K$(p,\gamma)^{36}$Ca reaction does not affect the shape of the X-ray burst light curve, and that it can be removed from the list of the few influential proton radiative captures reactions having a strong impact on the light curve.

Background: Spatially correlated overabundances of N-15 and O-18 observed in some low-density graphite meteoritic grains have been connected to nucleosynthesis taking place in the helium-burning shell during core-collapse supernovae. Two of the reactions which have been identified as important to the final abundances of N-15 and O-18 are F-18(n, alpha) N-15 and F-18(n, p) O-18. The relative strengths of the F-18(n, alpha) N-15 and F-18(n, p) O-18 reactions depend sensitively on the relative alpha(0) and p(0) decay branches from states above the neutron threshold in F-19 in addition to other properties such as the spins, parities, and neutron widths. However, experimental data on the charged-particle decays from these highly excited states are lacking or inconsistent. Purpose: We measure the charged-particle decay branches from states around the neutron threshold in F-19. Method: Two experiments were performed using proton inelastic scattering from LiF targets and magnetic spectrographs. The first experiment used the high-resolution Q3D spectrograph at Munich to constrain the properties of levels in F-19. A second experiment using the Orsay split-pole spectrograph and an array of silicon detectors was performed in order To measure the charged-particle decay branches from states around the neutron threshold in F-19. Results: A number of levels in F-19 have been identified along with their corresponding charged-particle decays. The first state above the neutron threshold which has an observed proton-decay branch to the ground state of O-18 lies 68 keV (E-x = 10.5 MeV) above the neutron threshold. The alpha-particle decays from the neutron-unbound levels are generally observed to be much stronger than the proton decays. Conclusion:Neutron-unbound levels in F-19 are observed to decay predominantly by a-particle emission, supporting the role of F-18(n, alpha) N-15 in the production of N-15 in the helium-burning shell of supernovae. Improved resonant-scattering reaction data are required in order to be able to determine the reaction rates accurately.

The SPIRAL1 (Systeme de Production d'Ions Radioactifs Acceleres en Ligne) facility at GANIL (Grand Accelerateur National d'Ions Lourds) is developing new techniques to access nuclei in the neutron-deficient isotope region far from the stability-valley, with Z ranging from 30 to 60. The availability of different primary beams, ranging from carbon to uranium with energies up to 95 MeV/A, gives an opportunity to produce a large variety of radioactive ion beams. The production of neutron-deficient short-lived alkalis by fusion-evaporation reactions is the focus of this work. A simple and compact target ion source system (TISS) is designed to produce isotopes of Rb-74 (tau(1/2) = 64.8 ms) and Cs-114 (tau(1/2) = 570 ms). The efficiencies of the different processes involved in the production are evaluated. Radioactive recoils are produced through the interaction of heavy-ion beams, respectively Ne-20 beam and Ni-58 beam at an intensity of 10(13) and 10(12) pps, with a thin Ni-58 target. High atom-to-ion transformation (ATI) efficiency should be obtained above 70% and 90% for Rb-74 and Cs-114 nuclei respectively. The expected intensities of the RIBs are estimated to be around 10(4) pps at the exit of the TISS.

for neutrinoless double beta decay of Sn A. Shrivastava1,2,∗ K. Mahata, I. Stefan, M. Assie, P. Adsley, D. Beaumel, V.M. Datar, A. Georgiadou, J. Guillot, F. Hammache, N. Keeley, Y.H. Kim, A. Meyer, V. Nanal, V.V. Parkar, and N. de Sereville Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India Institut de Physique Nucl eaire dOrsay, UMR8608, IN2P3-CNRS, Universit e Paris Sud, 91406 Orsay, France Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai 400005, India National Centre for Nuclear Research, ul. Andrzeja Sotana 7, 05-400 Otwock, Poland and GANIL, CEA/DRF CNRS/IN2P3, Bd Henri Becquerel, BP 55027, F-14076 Caen Cedex 5,France

The TETRA long neutron counter is operated at ALTO ISOL facility behind the PARRNe mass separator. TETRA has been proven to be a unique instrument for measurements of beta-decay properties of short-lived neutron-rich nuclei having applications for the nuclear structure and/or astrophysical r-process calculations. A proper calibration of TETRA can allow validation of the experimental procedure used for determination of beta-delayed one-neutron emission probabilities (P-1n). It requires the use of a well-known beta-neutron decaying radioactive source which can be only produced and measured on-line due to its short half-life. Thus, the present paper reports on measurements of P-1n and T(1/2 )of Rb-96,Rb-97 nuclei using TETRA. The results obtained are in a good agreement with the values available in the literature. This proves that the developed techniques can be applied to unknown P-1n and T-1/2 of neutron-rich species.

The \(^{30}\)P(p,\(\gamma \))\(^{31}\)S reaction is one of the few remaining reactions whose rate uncertainty has a strong impact on classical novae model predictions. To reduce the nuclear uncertainties associated to this reaction, we measured the \(^{31}\)P(\(^{3}\)He,t)\(^{31}\)S reaction at the ALTO facility. Simultaneous detection of the triton and proton decays from the populated resonances will provide the proton branching ratios. The astrophysical context of this work, the current situation of the \(^{30}\)P(p,\(\gamma \))\(^{31}\)S reaction rate, the experimental set-up and the analysis of the single and coincidence events will be presented.

Neutron-capture reactions on \(^{18}\)F in the helium-burning shell play an important role in the production of \(^{15}\)N during core-collapse supernovae. The competition between the \(^{18}\)F(\(n,p/\alpha \))\(^{18}\)O/\(^{15}\)N reactions controls the amount of \(^{15}\)N produced. The strengths of these reactions depend on the decay branching ratios of states in \(^{19}\)F above the neutron threshold. We report on an experiment investigating the decay branching ratios of these states in order to better constrain the strengths of the reactions.