
AlDahan, N. et al, Algora, A., Molina, F., & Rubio, B. (2012). Multiple beta() decaying states in Re194: Shape evolution in neutronrich osmium isotopes. Phys. Rev. C, 85(3), 034301–9pp.
Abstract: beta decays from heavy, neutronrich nuclei with A similar to 190 have been investigated following their production via the relativistic projectile fragmentation of an E/A = 1 GeV Pb208 primary beam on a similar to 2.5 g/cm(2) Be9 target. The reaction products were separated and identified using the GSI FRagment Separator (FRS) and stopped in the RISING active stopper. gamma decays were observed and correlated with these secondary ions on an eventbyevent basis such that gammaray transitions following from both internal (isomeric) and beta decays were recorded. A number of discrete, betadelayed gammaray transitions associated with beta decays from Re194 to excited states in Os194 have been observed, including previously reported decays from the yrast Ipi = (6(+)) state. Three previously unreported gammaray transitions with energies 194, 349, and 554 keV are also identified; these transitions are associated with decays from higher spin states in Os194. The results of these investigations are compared with theoretical predictions from Nilsson multiquasiparticle (MQP) calculations. Based on lifetime measurements and the observed feeding pattern to states in Os194, it is concluded that there are three beta()decaying states in Re194.



Algora, A. et al, Jordan, D., Tain, J. L., Rubio, B., Agramunt, J., PerezCerdan, A. B., et al. (2011). Improvements on Decay Heat Summation Calculations by Means of Total Absorption Gammaray Spectroscopy Measurements. J. Korean Phys. Soc., 59(2), 1479–1482.
Abstract: The decay heat of fission products plays an important role in predictions of the heat released by nuclear fuel in reactors. In this contribution we present results of the analysis of the measurement of the beta decay of some refractory isotopes that were considered possible important contributors to the decay heat in reactors. The measurements presented here were performed at the IGISOL facility of the University of Jyvaskyla, Finland. In our measurements we have combined for the first time a Penning trap (JYFLTRAP), which was used as a high resolution isobaric separator, with a total absorption spectrometer. The results of the measurements as well as their consequences for decay heat summation calculations are discussed.



Algora, A. et al, Jordan, D., Tain, J. L., Rubio, B., Agramunt, J., PerezCerdan, A. B., et al. (2010). Reactor Decay Heat in Pu239: Solving the gamma Discrepancy in the 43000s Cooling Period. Phys. Rev. Lett., 105(20), 202501–4pp.
Abstract: The beta feeding probability of Tc102,Tc 104,Tc 105,Tc 106,Tc 107, Mo105, and Nb101 nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a longstanding discrepancy in the gamma component of the decay heat for Pu239 in the 43000 s range.



Algora, A. et al, Valencia, E., Tain, J. L., Jordan, M. D., Agramunt, J., Rubio, B., et al. (2014). Total Absorption Study of Beta Decays Relevant for Nuclear Applications and Nuclear Structure. Nucl. Data Sheets, 120, 12–15.
Abstract: An overview is given of our activities related to the study of the beta decay of neutron rich nuclei relevant for nuclear applications. Recent results of the study of the beta decay of Br87,Br88 using a new segmented total absorption spectrometer are presented. The measurements were performed at the IGISOL facility using trapassisted total absorption spectroscopy.



Denis Bacelar, A. M. et al, Algora, A., Molina, F., & Rubio, B. (2013). The population of metastable states as a probe of relativisticenergy fragmentation reactions. Phys. Lett. B, 723(45), 302–306.
Abstract: Isomeric ratios have been measured for highspin states in Po198,200,206,208(84), At208,209,210,211(85), Rn210,211,212,213,214(86), Fr208,211,212,213,214(87), Ra210,211,212,214,215(88), and Ac215(89) following the projectile fragmentation of a 1 AGeV U238 beam by a Be9 target at GSI Helmholtzzentrum fur Schwerionenforschung. The fragments were separated in the fragment separator (FRS) and identified by means of energy loss and timeofflight techniques. They were brought to rest at the centre of the RISING gammaray detector array and intensities of gamma rays emitted in the decay of isomeric states with halflives between 100 ns and 40 μs and spin values up to 55/2 (h) over bar were used to obtain the corresponding isomeric ratios. The data are compared to theoretical isomeric ratios calculated in the framework of the abrasionablation model. Large experimental enhancements are obtained for highspin isomers in comparison to expected values.



Fujita, H. et al, Algora, A., EstevezAguado, E., Molina, F., & Rubio, B. (2019). Experimental study of GamowTeller transitions via the highenergyresolution O18(He3, t)F18 reaction: Identification of the lowenergy “super” GamowTeller state. Phys. Rev. C, 100(3), 034618–13pp.
Abstract: Using the highresolution O18(He3, t)F18 reaction at 0 degrees and at 140 MeV/nucleon, GamowTeller (GT) transitions were studied. A high energy resolution of 31 keV was achieved by applying dispersion matching techniques. The main part of the observed GT transition strength is concentrated in the transition to the F18 ground state (g.s.). The absolute values of the reduced GT transition strengths, B(GT), were derived up to Ex = 12 MeV assuming proportionality between the B(GT) values and the reaction cross sections at 0 degrees. The B(GT) value obtained from the beta decay of F18 (g.s.) > O18 (g.s.) was used to determine the proportionality constant. A total B(GT) of 4.06(5) was found and 76(1)% of the strength is concentrated to the ground state of F18. The obtained B(GT) values were compared with those from the O18(p, n) F18 reaction and the mirror symmetric beta(+) decay of Ne18 > F18. The candidates for 1(+) states with isospin T = 1 were identified by comparison with the O18(p, p') data. The results of shellmodel and quasiparticlerandomphase approximation calculations suggest constructive contributions of various configurations to the F18 ground state, suggesting that this state is the lowenergy super GT state.



Fujita, Y. et al, Algora, A., EstevezAguado, E., Molina, F., & Rubio, B. (2014). Observation of Low and HighEnergy GamowTeller Phonon Excitations in Nuclei. Phys. Rev. Lett., 112(11), 112502–5pp.
Abstract: GamowTeller (GT) transitions in atomic nuclei are sensitive to both nuclear shell structure and effective residual interactions. The nuclear GT excitations were studied for the mass number A = 42, 46, 50, and 54 “fshell” nuclei in (He3, t) chargeexchange reactions. In the Ca42 > Sc42 reaction, most of the GT strength is concentrated in the lowest excited state at 0.6 MeV, suggesting the existence of a lowenergy GT phonon excitation. As A increases, a highenergy GT phonon excitation develops in the 611 MeV region. In the Fe54 > Co54 reaction, the highenergy GT phonon excitation mainly carries the GT strength. The existence of these two GT phonon excitations are attributed to the 2 fermionic degrees of freedom in nuclei.



Fujita, Y. et al, Algora, A., EstevezAguado, E., Molina, F., & Rubio, B. (2013). Highresolution study of Tz =+2 >+1 GamowTeller transitions in the Ca44(3He,t)Sc44 reaction. Phys. Rev. C, 88(1), 014308–18pp.
Abstract: In order to study the GamowTeller (GT) transitions from the Tz = +2 nucleus Ca44 to the Tz = +1 nucleus Sc44, where Tz is the z component of isospin T, we performed the (p, n)type (He3, t) chargeexchange (CE) reaction at 140 MeV/nucleon and the scattering angles 0 degrees and 2.5 degrees. 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 sumrulelimit 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 beta decay of Cr44 to V44. First, we confirmed that the betadecay halflife T1/2 of Cr44 can be reproduced using the B(GT) distribution from the Ca44(He3, t) measurement. Then, the 0 degrees, (3He, t) spectrum was modified to deduce the “betadecay spectrum” and it was compared with the delayedproton spectrum from the Cr44 beta 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 Ca44(p, p') reaction can excite spinM1 states (states populated by spinM1 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 = 11.513.7 MeV region. (iii) It has been suggested that the T = 2, J(pi) = 0(+) double isobaric analog state (DIAS) at 9.338 MeV in the Tz = 0 nucleus Ti44 forms an isospinmixed doublet with a subsidiary 0(+) state at 9.298 MeV. Since no corresponding state was found in the Tz = +1 nucleus Sc44, we suggest T = 0 for the subsidiary state.



Fujita, Y., Rubio, B., Adachi, T., Blank, B., Fujita, H., Gelletly, W., et al. (2015). GamowTeller excitations studied by weak and strong interactions. Acta Phys. Pol. B, 46(3), 657–668.
Abstract: Studying weak nuclear responses, especially the GamowTeller (GT) transitions starting from stable as well as unstable nuclei, provide crucial and critical information on nuclear structure. Therefore, the study of GT transitions is a key issue in nuclear physics and also nuclearastrophysics. Under the assumption of isospin symmetry, it is expected that the structure of mirror nuclei and the GT transitions starting from their ground states are identical. We have studied the corresponding GT transitions starting from Tz = +/ 1 and +/ 2 p f shell nuclei, respectively, by means of hadronic (He3,t) chargeexchange reactions and mirror beta decays. The results on GT strength distributions measured in beta decays and (He3,t) reactions performed at an intermediate incident energy of 140 MeV/nucleon and 0 degrees are compared. The combined results help provide an understanding of nuclear structure of nuclei farfromstability.



Fujita, Y., Rubio, B., Molina, F., Adachi, T., Fujita, H., Blank, B., et al. (2016). The Tz = Â±1 â†’ 0 and Â±2 â†’Â±1 Mirror Gamowâ€“Teller transitions in pfshell nuclei. Acta Phys. Pol. B, 47(3), 867–881.
Abstract: GamowTeller (GT) transitions are the most common weakinteraction processes in the Universe. They play important roles in various processes of nucleosynthesis, for example, in the rapid protoncapture process (rpprocess). In the pfshell region, the rpprocess runs through neutrondeficient 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 been studying the Tz = 2 > 1 and 1 > 0 GT transitions in beta decays, while those from stable Tz = +2 and +1 nuclei by means of hadronic (He3; t) chargeexchange (CE) reactions. The results from these studies are compared in order to examine the mirrorsymmetry structure in nuclei. In addition, these results are combined for the better understanding of GT transitions in the pfshell region.

