Geissel, H.

Rappold, C.

Saito, T.

Scheidenberger, C.

GSI Repository

Experimental setup for hypernuclear study at the Super-FRSC.Rappold∗1,2, T.R. Saito1,3,4, C. Scheidenberger1,2, and H. Geissel1,21GSI, Darmstadt, Germany; 2Justus-Liebig-Universita¨t Giessen, Germany; 3Johannes Gutenberg-Universita¨t, Mainz,Germany; 4The Helmholtz Institute Mainz, Mainz, GermanyThe first experiment of the HypHI collaboration aimedto demonstrate the feasibility of the hypernuclear spec-troscopy by means of heavy ion beam induced reactions.The final results show that the experimental method is vi-able for the study of hypernuclei [1, 2]. For this first experi-ment a 6Li beam at 2AGeV on a Carbon target was used. Asecond experiment with a 20Ne beam with the similar con-dition was also performed, preliminary results show thatagain Λ hyperon and 3ΛH were identifiable.A new set of experiments at FRS fragment separator isunder study [3, 4]. The design study for a first experimentat FRS is on-going, which the experiment would focus ondemonstrate this time that a hypernuclear spectroscopy canbe performed within the FRS. A new dedicated apparatusfor exclusive measurement can be set up within the frag-ment separator FRS, in contrast to the experimental appa-ratus devoted to inclusive measurement of the first experi-ments of the HypHI project. In this report, the first designof the experimental apparatus that could be placed into S2area of FRS will be presented. The aim of the first experi-ment would the use a 6Li beam on the carbon target in or-der to produce the 4ΛH hypernucleus as a reference speciessince it has been already identified in the phase 0 exper-iment. It will be considered as a benchmark to show thefeasibility of the hypernuclear spectroscopy within FRS.Secondly, nnΛ bound state can be also search again forconfirming its existence.At S2 area, a detection apparatus consisting of a coupleof dipole magnets could be install in order to separate thepi− meson of the mesonic weak decay of produced hyper-nuclei, while the positively charged fragments would enterthe second part of FRS for precise determination of theirmomentum. The second dipole magnet is placed in sucha way that it will correct the deflection of the fragmentsinduced by the first dipole magnet in order to allow themto enter on beam axis the second part of the FRS. Detec-tors that have been already developed for the first exper-iment of the HypHI project can used in a similar way totrack charged particles around the decay volume. Thus,the fiber detectors and drift chamber could be place in theupstream of the first magnets. The pi− mesons are then de-tected with a set of hodoscope walls and drift chambers inorder to complete the information needed for the track re-construction. Complete design of the detection apparatusis still on-going, which aims to minimize the pion multi-scattering within the detection layers to improve as much∗ c.rappold@gsi.deas possible the momentum resolution of the pions.The transport optics calculated and simulated by MO-CADI, is also used in order to determine the momentumand geometrical acceptance of the fragment within the sec-ond part of the FRS. Currently, the simulation code for theMonte Carlo simulation of the apparatus at S2 is coupledwith the MOCADI code: at first the full set of events isproduced and propagated up to the entrance of the secondpart of the FRS, then those events are set as input for theMOCADI simulation code. At the end, event per event,and fragment per fragment within the event, the fragmenttransport through S2 to S4 is performed and registered. Thefinal acceptance is then estimated. Coupling the two codewill allow us to determine the trigger rate and hypernuclearyield that could be expected during such experiment. Thoseestimations are still on-going. The optics of the couple ofdipole magnets with the first magnet stage of the secondpart of the FRS (S2-S4) is also under investigation.Figure 1: 3D view of the experimental apparatus at S2 areaof the FRS. The couple of dipole magnets is shown withthe simulated events of deuteron and pi− meson from thennΛ decay.References[1] C. Rappold et al., Nucl. Phys. A 913, 170 (2013).[2] C. Rappold et al., Phys. Rev. C 88, 041001 (2013).[3] C. Rappold et al., GSI Scientific Report 2012 [GSI Report2013-1] (2013) p. 176.[4] C. Rappold et al., GSI Scientific Report 2013 [GSI Report2014-1] (2014) p. 101.MU-NUSTAR-FRS-02 GSI SCIENTIFIC REPORT 2014136 DOI:10.15120/GR-2015-1-MU-NUSTAR-FRS-02

Experimental setup for hypernucleat study at the Super-FRS

http://repository.gsi.de/record/183899/files/MU-NUSTAR-FRS-02.pdf

Experimental setup for hypernucleat study at the Super-FRS

Abstract

Similar works

Full text

Available Versions

GSI Repository