Low-energy Coulomb excitation of 62^{62}Fe and 62^{62}Mn following in-beam decay of 62^{62}Mn

Sub-barrier Coulomb-excitation was performed on a mixed beam of $^{62}$Mn and $^{62}$Fe, following in-trap $\beta^{-}$ decay of $^{62}$Mn at REX-ISOLDE, CERN. The trapping and charge breeding times were varied in order to alter the composition of the beam, which was measured by means of an ionisation chamber at the zero-angle position of the Miniball array. A new transition was observed at 418~keV, which has been tentatively associated to a $(2^{+},3^{+})\rightarrow1^{+}_{g.s.}$ transition. This fixes the relative positions of the $\beta$-decaying $4^{+}$ and $1^{+}$ states in $^{62}$Mn for the first time. Population of the $2^{+}_{1}$ state was observed in $^{62}$Fe and the cross-section determined by normalisation to the $^{109}$Ag target excitation, confirming the $B(E2)$ value measured in recoil-distance lifetime experiments.Comment: 9 pages, 10 figure

Study of bound states in 12Be through low-energy 11Be(d,p)-transfer reactions

The bound states of 12Be have been studied through a 11Be(d,p)12Be transfer reaction experiment in inverse kinematics. A 2.8 MeV/u beam of 11Be was produced using the REX-ISOLDE facility at CERN. The outgoing protons were detected with the T-REX silicon detector array. The MINIBALL germanium array was used to detect gamma rays from the excited states in 12Be. The gamma-ray detection enabled a clear identification of the four known bound states in 12Be, and each of the states has been studied individually. Differential cross sections over a large angular range have been extracted. Spectroscopic factors for each of the states have been determined from DWBA calculations and have been compared to previous experimental and theoretical results

Search for proton emission of the isomeric 10+ state in 54 Ni

9 pags., 7 figs., 1 tab.Several experiments were conducted at the 10 MV Van-de-Graaff tandem accelerator at the Institute of Nuclear Physics, Cologne, to detect proton emission from the isomeric 6457-keV 10 state in Ni. Excitation functions for two fusion–evaporation reactions were measured to maximise the population of the rare two-neutron evaporation channel from a Ni compound nucleus. The search for delayed proton emission was based on the Si (Si , 2 n)Ni reaction at a beam energy of 70 MeV. For this reaction, a cross-section limit for the population of the 10 state in Ni and its proton-decay branch was determined to be σ< 22 nb.Open Access funding provided by Projekt DEAL. We would like to thank the accelerator staff at the University of Cologne for the efforts to deliver heavy-ion beams of excellent quality, as well as the Swedish Research Council (contract VR 2008-4240 and VR 2016- 3969) for financial support

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Quadrupole collectivity in neutron-rich Cd isotopes

4 pags., 2 figs. -- INPC 2013 – International Nuclear Physics ConferenceThe investigation of the excitation energies of the 21+ –states in the neutron-rich Cd isotopes shows an irregular behaviour when approaching the neutron shell-closure at N = 82. The energy of the 21+–state in 128Cd is lower than the one in 126Cd. The transition strength B(E2, 0gs+ → 21+) in the even isotopes 122−128Cd was measured in Coulomb excitation experiments with the high-purity germanium detector array MINIBALL at REXISOLDE (CERN). The values for 122,124Cd coincide with beyond-mean-field calculations with a resultant prolate deformation, whereas 126,128Cd are better described by shell-model calculations.This project is supported by BMBF (No. 06 DA 9036I, No. 05 P12 RDCIA, No. 05 P12 RDCIB and No. 05 P12 PKFNE), HIC for FAIR, EU through EURONS (No. 506065) and ENSAR (No. 262010) and the MINIBALL and REX-ISOLDE collaborations

Study of bound states in Be-10 by one neutron removal reactions of Be-11

The bound states of Be-10 have been studied by removing single neutrons from Be-11 nuclei. A 2.8 MeV u(-1) beam of Be-11 was produced at ISOLDE, CERN and directed on to both proton and deuteron targets inducing one-neutron removal reactions. Charged particles were detected to identify the two reaction channels (d, t) and (p, d), and the individual states in Be-10 were identified by gamma detection. All bound states but one were populated and identified in the (d, t) reaction. The combination of REX-ISOLDE and MINIBALL allowed for a clean separation of the high-lying states in Be-10. This is the first time these states have been separated in a reaction experiment. Differential cross sections have been calculated for all the reaction channels and compared to DWBA calculations. Spectroscopic factors are derived and compared to values from the litterature. While the overall agreement between the spectrocopic factors is poor, the ratio between the ground state and the first excited state is in agreement with the previous measured ones. Furthermore, a significant population of the 2(2)(+) state is observed, which which may indicate the presence of multi-step processes at our beam energy.Peer reviewe

Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector

Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente

Collectivity in Pb-196,Pb-198 isotopes probed in Coulomb-excitation experiments at REX-ISOLDE

The neutron-deficient Pb-196,Pb-198 isotopes have been studied in Coulomb-excitation experiments employing the Miniball gamma-ray spectrometer and radioactive ion beams from the REX-ISOLDE post-accelerator at CERN. The reduced transition probabilities of the first excited 2(+) states in Pb-196 and Pb-198 nuclei have been measured for the first time. Values of B (E2) = 18.2(-4.1)(+4.8) W. u. and B (E2) = 13.1(-3.5)(+4.9) W. u., were obtained, respectively. The experiment sheds light on the development of collectivity when moving from the regime governed by the generalised seniority scheme to a region, where intruding structures, associated with different deformed shapes, start to come down in energy and approach the spherical ground state.Peer reviewe