G. Ickert

Performance of upstream interaction region detectors for the FIRST experiment at GSI

The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at GSI has been designed to study carbon fragmentation, measuring 12C double differential cross sections (∂2σ/∂θ∂E) for different beam energies between 100 and 1000 MeV/u. The experimental setup integrates newly designed detectors in the, so called, Interaction Region around the graphite target. The Interaction Region upstream detectors are a 250 μm thick scintillator and a drift chamber optimized for a precise measurement of the ions interaction time and position on the target. In this article we review the design of the upstream detectors along with the preliminary results of the data taking performed on August 2011 with 400 MeV/u fully stripped carbon ion beam at GSI. Detectors performances will be reviewed and compared to those obtained during preliminary tests, performed with 500 MeV electrons (at the BTF facility in the INFN Frascati Laboratories) and 80 MeV/u protons and carbon ions (at the INFN LNS Laboratories in Catania).

FIRST experiment: Fragmentation of Ions Relevant for Space and Therapy

Nuclear fragmentation processes are relevant in different fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications. The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at SIS accelerator of GSI laboratory in Darmstadt, has been designed for the measurement of different ions fragmentation cross sections at different energies between 100 and 1000 MeV/nucleon. The experiment is performed by an international collaboration made of institutions from Germany, France, Italy and Spain. The experimental apparatus is partly based on an already existing setup made of the ALADIN magnet, the MUSIC IV TPC, the LAND2 neutron detector and the TOFWALL scintillator TOF system, integrated with newly designed detectors in the interaction Region (IR) around the carbon removable target: a scintillator Start Counter, a Beam Monitor drift chamber, a silicon Vertex Detector and a Proton Tagger for detection of light fragments emitted at large angles (KENTROS). The scientific program of the FIRST experiment started on summer 2011 with the study of the 400 MeV/nucleon 12C beam fragmentation on thin (8mm) carbon target.

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

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.

Performance of timing resistive plate chambers with relativistic neutrons from 300 to 1500 MeV

A prototype composed of four resistive plate chamber layers has been exposed to quasi-monoenergetic neutrons produced from a deuteron beam of varying energy (300 to 1500 AMeV) in experiment S406 at GSI, Darmstad, Germany. Each layer, with an active area of about 2000 × 500 mm2, is made of modules containing the active gaps, all in multigap construction. Each gap is defined by 0.3 mm nylon mono-filaments positioned between 2.85 mm thick float glass electrodes. The modules are operated in avalanche mode with a non-flammable gas mixture composed of 90% C2H2F4 and 10% SF6. The signals are readout by a pick-up electrode formed by 15 copper strips (per layer), spaced at a pitch of 30 mm, connected at both sides to timing front end electronics. Measurements of the time of flight jitter of neutrons, in the mentioned energy range, point to a contribution of the resistive plate chamber in the order of 150 ps, independent of the neutron energy.

The FIRST experiment for nuclear fragmentation measurements at GSI

Nuclear fragmentation processes are relevant in different fields of physics concerning both basic research and applications. FIRST (Fragmentation of Ions Relevant for Space and Therapy) is an experiment aimed at the measurement of double differential cross sections (DDCS), with respect to kinetic energy and scattering polar angle, of nuclear fragmentation processes relevant for hadron therapy and for space radiation protection applications, in the energy range between 100 and 1000 MeV/u. The experiment was mounted at the GSI laboratories of Darmstadt, in Germany. A first data taking was performed in August 2011, using 400 MeV/u 12C on carbon and gold targets. In this work we present a description of the experimental apparatus and some figures from the data acquisition and from the preliminary work on data analysis.

Coulomb dissociation reactions on Mo isotopes for astrophysics applications

Photo-dissociation reactions play an important role in p-process nucleosynthesis, which takes place in supernova explosions. Theoretical calculations of isotopic abundances of the p-nuclei require a vast reaction network linking thousands of isotopes, where most of the reaction rates must be derived from the Hauser-Feshbach statistical model. However, as many rates as possible need to be determined experimentally, in order to provide a reliable reference for the calculations. Measuring reaction rates on Mo isotopes is important to explain the problem of the significant underproduction of Mo and Ru in all existing models of p-process nucleosynthesis. Another aspect of the project is to verify the accuracy of the Coulomb dissociation method by comparing our data with experiments performed with real photons at S-DALINAC (TU Darmstadt) and ELBE (FZD) [1].

Measurement of the Mo-92,Mo-93,Mo-94,Mo-100(gamma,n) reactions by Coulomb Dissociation

The Coulomb Dissociation (CD) cross sections of the stable isotopes Mo-92,Mo-94,Mo-100 and of the unstable isotope Mo-93 were measured at the LAND/(RB)-B-3 setup at GSI Helmholtzzentrum fur Schwerionenforschung in Darmstadt, Germany. Experimental data on these isotopes may help to explain the problem of the underproduction of Mo-92,Mo-94 and Ru-96,Ru-98 in the models of p-process nucleosynthesis. The CD cross sections obtained for the stable Mo isotopes are in good agreement with experiments performed with real photons, thus validating the method of Coulomb Dissociation. The result for the reaction Mo-93(gamma,n) is especially important since the corresponding cross section has not been measured before. A preliminary integral Coulomb Dissociation cross section of the Mo-94(gamma,n) reaction is presented. Further analysis will complete the experimental database for the (gamma,n) production chain of the p-isotopes of molybdenum.

Progress report of the CALIFA/

D. Cortina-Gil †1, H. Alvarez-Pol1, T. Aumann13, V. Avdeichikov4, M. Bendel7, J. Benlliure1, D. Bertini5, A. Bezbakh11, T. Bloch13, M. Böhmer7, M.J.G. Borge2, J.A. Briz2, P. Cabanelas1, E. Casarejos8, M. Carmona Gallardo2, J. Cederkäll4, L. Chulkov12, M. Dierigl7, D. Di Julio4, I. Durán1, E. Fiori10, A. Fomichev11, D. Galaviz9, M. Gascón1, R. Gernhäuser7, J. Gerl5, P. Golubev4, M. Golovkov11, D. González1, A. Gorshkov11, A. Heinz3, M. Heil5, B. Heiss7, W. Henning7, G. Ickert5, A. Ignatov13, B. Jakobsson4, H.T. Johansson3, M. Kmiecik14, Th. Kröll13, R. Krücken ‡ 7, S. Krupko11, F. Kurz7, T. Le Bleis7, B. Löher10, A. Maj14, E. Nacher2, T. Nilsson3, A. Perea2, C. Pfeffer7, N. Pietralla13, B. Pietras1, R. Reifarth6, J. Sanchez del Rio2, D. Savran10, S. Sidorchuk11, H. Simon5, L. Schnorrenberger13, O. Tengblad2, P. Teubig9, R. Thies3, J.A. Vilán8, M. von Schmid13, M. Winkel7, S. Winkler7, F. Wamers13, P. Yañez8, and M. Zieblinski14 1Universidad de Santiago de Compostela; 2Instituto Estructura de la Materia, CSIC Madrid; 3Chalmers University of Technology, Göteborg; 4Lund University; 5Helmholtzzentrum für Schwerionenforschung, Darmstadt; 6Goethe University Frankfurt am Main; 7Technische Universität München; 8Universidad de Vigo; 9Centro de Física Nuclear da Universidade de Lisboa; 10Extreme Matter Institute and Research Division, GSI; 11Joint Institute for Nuclear Research, Dubna; 12Nuclear Reseach Center, Kurchatov Institute Moscow; 13Technische Universität Darmstadt; 14Institute of Nuclear Physics PAN, Krakow, Poland

R^3B

The knowledge about fragmentation processes in ion-ion interactions is fundamental in hadrontherapy and radiation protection in space missions. Hadrontherapy, based on 12C, features many advantages with respect to conventional radiation therapy with photons due to the possibility to shape the dose delivery region in tissues but side effects of the projectile fragmentation in healthy tissues are not negligible. NASA recently pointed out that measurements for some light ions and kinetic energies are missing in nuclear fragmentation databases. FIRST experiment aims to measure the fragmentation double differential cross section of 12C in the energy range 1001000 MeV/u on several elements, constituents of organic tissues and electronic devices, in order to fill some of the mentioned lack of information on light ions. A first set of data has been taken in 2011 at GSI (Darmstadt), using 12C beam at 400 MeV/u on C and Au targets. About 3·107 events with C target and 5 · 106 with Au target were recorded. Together with these data other sets of runs have been collected to calibrate the forward part of the whole experimental setup, the ToF-Wall. The calibration procedure and the detector performances, which fit the experiment requirements for what concerns efficiency, resolution and stability, will be illustrated. Moreover, some preliminary results concerning the 12C-12C elastic scattering, in agreement with the Rutherford model, will be presented.

calorimeter

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.