Scintillating fiber detectors for the HypHI project at GSI

WOS: 000270326800009The construction and properties of three sets of two-dimensional scintillating fiber detector arrays for tracking of charged particles used in the HypHI Phase 0 experiment at GSI will be reported in this paper. The position resolutions and the detection efficiency of detectors have been obtained for each layer of detectors by using Li-6 primary beams and particles with Z = 1 produced by fragment reactions of Xe-136 projectiles on the hydrogen target. Besides, the response of energy deposition of charged particles in the first detector set placed right behind the target has been studied by using light projectile fragments with Z = 1, 2 and 3 produced by Ni-58 and C-12 beams. Extracted resolutions for energy deposition and position as well as the detection efficiency fulfill the requirements of the HypHl Phase 0 experiment. (C) 2009 Elsevier B.V. All rights reserved.Helmholtz association as Helmholtz-University Young Investigators Group [VH-NG-239]; German Research Foundation (DFG) [SA 1696/1-1]; Ministry of Education, Science and Culture of Japan [18042008]; EU FP7 HadronPhysic2 SPHEREWe would like to thank the accelerator department at GSI for providing us beams with excellent conditions. We would also thank H. lwase, R. Pleskac and D. Schardt to help us during the experiment in cave A at GSI. We would like to show our appreciation to the FOPI and SPALADIN collaboration to provide us beams behind their experimental setups. We would also like to show our gratitude to the Detector Laboratory at GSI, Electronics Department of the Institute for Nuclear Physics of Mainz University, the Experimental Electronics Department at GSI and the Target Laboratory at GSI for their supports for the development. The HypHI project is funded by the Helmholtz association as Helmholtz-University Young Investigators Group VH-NG-239 at GSI, and German Research Foundation (DFG) with a contract number SA 1696/1-1. The authors acknowledge financial support by the Ministry of Education, Science and Culture of Japan, Grantin-Aid for Scientific Research on Priority Areas 449. This work is also supported by the Ministry of Education, Science and Culture of Japan, Grant-in-Aids for Scientific Research 18042008 and EU FP7 HadronPhysic2 SPHERE

Summary of the HypHI Phase 0 experiment and future plans with FRS at GSI (FAIR Phase 0)

WOS: 000381331200014Results of the HypHI Phase 0 experiment with the reaction of Li-6+C-12 at 2 A GeV are summarised. Invariant mass distributions as well as,the lifetime measurements for H-3(Lambda) and H-4(Lambda) are discussed. The lifetime values for both the hypernuclei are respectively observed to be 18(-32)(+42) ps and 140(-33)(+48) ps, being significantly shorter than those of the Lambda-hyperon. Statistical analyses of existing lifetime data for H-3(Lambda) up to 2014 confirm a significantly short lifetime of H-3(Lambda), which is not explained by present models. Observed hypernuclear production cross section values for H-3(Lambda) and H-4(Lambda) are also summarised. In addition, observed signals for the final states of d + pi(-) and t + pi(-) are discussed. All the discussions on the results of the HypHI Phase 0 experiment in this article are based on [1-4]. We also present a new proposed experiment with the FRS (FRagment Separator) at GSI (FAIR Phase 0) to improve the precision of the hypernuclear spectroscopy with peripheral heavy ion induced reactions. (C) 2016 Elsevier B.V. All rights reserved.GSI Department of Accelerator; GSI Department of Experimental Electronics; GSI Department of the Detector Laboratory; GSI Department of the Target Laboratory; Electronics Department of the Institute for Nuclear Physics of Mainz University; Helmholtz association as Helmholtz-University Young Investigators Group [VH-NG-239]; German Research Foundation (DFG) [SA 1696/1-1]; Ministry of Education, Culture, Sports, Science, and Technology [449, 18042008]; EU FP7 Hadron-Physics-2 SPHEREThe authors would like to thank the GSI Departments of Accelerator, of Experimental Electronics, of the Detector Laboratory and of the Target Laboratory and the Electronics Department of the Institute for Nuclear Physics of Mainz University for supporting the project. The HypHI project is funded by the Helmholtz association as Helmholtz-University Young Investigators Group VH-NG-239 at GSI, and the German Research Foundation (DFG) under contract number SA 1696/1-1. The authors acknowledge the financial support provided by the Ministry of Education, Culture, Sports, Science, and Technology, Grant-in-Aid for Scientific Research on Priority Areas 449, and Grant-in-Aid for promotion of Cooperative Research in Osaka Electro-Communication University (2004-2006). This work is also supported by the Ministry of Education, Culture, Sports, Science, and Technology, Grants-in-Aid for Scientific Research 18042008 and EU FP7 Hadron-Physics-2 SPHERE. A part of this work was carried out on the HIMSTER high performance computing infrastructure provided by the Helmholtz-Institute Mainz

Low-energy dipole strength in Sn-112,Sn-120

WOS: 000341166100003The Sn-112,Sn-120(gamma, gamma') reactions below the neutron separation energies have been studied at the superconducting Darmstadt electron linear accelerator S-DALINAC for different endpoint energies of the incident bremsstrahlung spectrum. Dipole strength distributions are extracted for Sn-112 up to 9.5 MeV and for Sn-120 up to 9.1 MeV. A concentration of dipole excitations is observed between 5 and 8 MeV in both nuclei. Missing strength due to unobserved decays to excited states is estimated in a statistical model. A fluctuation analysis is applied to the photon scattering spectra to extract the amount of the unresolved strength hidden in the background due to fragmentation. The strength distributions are discussed within different model approaches such as the quasiparticle-phonon model and the relativistic time blocking approximation, allowing for an inclusion of complex configurations beyond the initial particle-hole states. While a satisfactory description of the fragmentation can be achieved for sufficiently large model spaces, the predicted centroids and total electric dipole strengths for stable tin isotopes strongly depend on the assumptions about the underlying mean field.DAAD; DFG [SFB 634]; Alliance Program of the Helmholtz Association [HA216/EMMI]; BMBF [06GI9109]; US-NSF [PHY-1204486]; National Superconducting Cyclotron Laboratory at Michigan State UniversityR. Eichhorn and the S-DALINAC crew are thanked for their effort in providing excellent beams and the GSI for the loan of the enriched 112Sn target. We are grateful to V. Yu. Ponomarev for providing us with the results of his calculations and for important discussions. We are indebted to F. Siebenhuhner for his contribution to the analysis of the data. B.O-T. acknowledges financial support from the DAAD sandwich program during her stay in Germany. This work was supported by the DFG under Contract No. SFB 634, by the Alliance Program of the Helmholtz Association (HA216/EMMI), by BMBF Project No. 06GI9109, and by US-NSF Grant No. PHY-1204486 and the National Superconducting Cyclotron Laboratory at Michigan State University

Search for evidence of (3)(Lambda)n by observing d + pi(-) and t + pi(-) final states in the reaction of Li-6+C-12 at 2A GeV

<p>The experimental data obtained from the reaction of Li-6 projectiles at 2A GeV on a fixed graphite target were analyzed to study the invariant mass distributions of d + pi(-) and t + pi(-). Indications of a signal in the d + pi(-) and t + pi(-) invariant mass distributions were observed with significances of 5.3 sigma and 5.0 sigma, respectively, when including the production target, and 3.7 sigma and 5.2 sigma, respectively, when excluding the target. The estimated mean values of the invariant mass for d + pi(-) and t + pi(-) signal were 2059.3 +/- 1.3 +/- 1.7 MeV/c(2) and 2993.7 +/- 1.3 +/- 0.6 MeV/c(2) respectively. The lifetime estimation of the possible bound states yielding to d + pi(-) and t + pi(-) final states were deduced to be as 181(-24)(+30) +/- 25 ps and 190(-35)(+47) +/- 36 ps, respectively. Those final states may be interpreted as the two-body and three-body decay modes of a neutral bound state of two neutrons and a Lambda hyperon, (3)(Lambda)n.</p>

Hypernuclear spectroscopy of products from Li-6 projectiles on a carbon target at 2 A GeV

<p>A novel experiment, aiming at demonstrating the feasibility of hypernuclear spectroscopy with heavy ion beams, was conducted. Using the invariant mass method, the spectroscopy of hypernuclear products of Li-6 projectiles on a carbon target at 2 A GeV was performed. Signals of the Lambda-hyperon and H-3(Lambda) and H-4(Lambda) hypernuclei were observed for final states of p + pi(-), He-3 + pi(-) and He-4 + pi(-), respectively, with significance values of 6.7, 4.7 and 4.9 sigma. By analyzing the proper decay time from secondary vertex distribution with the unbinned maximum likelihood fitting method, their lifetime values were deduced to be 262(-43)(+56) +/- 45 ps for Lambda, 183(-32)(+42) +/- 37 ps for H-3(Lambda), and 140(-33)(+48) +/- 35 ps for H-4(Lambda). (c) 2013 Elsevier B.V. All rights reserved.</p>