Kaufeld, I.

Takechi, M.

Voss, B.

GSI Repository

Characterizing the SOFIA/ANDES TwinMUSIC ∗I. Kaufeld1,2, M. Takechi1, B. Voss1, for the SOFIA/ANDES-collaboration , and the FAIR@GSIRBDL1GSI, Darmstadt, Germany; 2Hochschule RheinMain, University of Applied Sciences, Ru¨sselsheim, GermanyPreliminary values for the resolutions of various fig-ures of merit have been deduced by the SOFIA TwinMU-SIC [1] for the spectra of isotopes obtained from the fissionof 238U. The energy-loss resolution was measured to beσΔEE= 0.34% with P25 gas (Fig. 1). This leads to a chargeresolution of σZ1,2 = 0.23± 0.01 for the measurements in12 of the TwinMUSIC and σZ1+2 = 0.31±0.02 for the sumof both. The steep falloff of Δt,10−90% ≈ 150ps of thedrift times close to the cathode measured for single anodesyields a corresponding resolution of the straight-line fit to atrack through the active volume of σdt,fit = (268± 40)ps(Fig. 2). For the electrical field settings applied the mea-sured drift velocity is well reproduced by Magboltz simula-tions. After fine adjustment of the drift-times with the helpof an adjacent MWPC, a position resolution for the singleanode of σx,PB = (28±11)μm and σx,FF = (47±13)μmfor the primary beam and fission fragments, respectively,can be deduced (Fig. 3). Consequently, the angular distri-bution of the fragments of ≈ 40mrad could be measuredwith a precision of σΘ,FF = (0.13± 0.10)mrad by event-wise tracking.The analysis of the data is still ongoing, further refinementson the achieved resolutions are to be expected. Isotopicmass yields have been be deduced and published elsewhere[2]. Changes in the design of the TwinMUSIC detector sys-tem are ongoing and will allow for an even better charge,position and angular resolution. We are aiming for a full3D tracking operation with rates of 1 − 2 MHz with anon-triggered DAQ. The potential of a low-pressure oper-ation (0.2 − 0.3atm) and the application of other, ’faster’gas mixtures will be tested too.The next physics run is already scheduled 2014 at CaveClooking into more details of the isotopic mass distributions.In the far future, a more complete set of measurements willbe performed in the context of R3B (Reaction studies withRelativistic Radioactive Beams) at the FAIR (Facility forAntiproton and Ion Research) project at GSI/Darmstadt.Dedicated detector developments will be performed forthose endeavors which foster similar developments e.g. forthe instrumentation of the SuperFRS.References[1] B.Voss et al., “Results from the SOFIA/ANDES TwinMU-SIC”, GSI Report 2013-1, p.204 (2013)[2] E. Pellereau et al., EPJ Web of Conferences 62, 06005 (2013)∗Work supported by FAIR@GSI PSP code: 2.4.Figure 1: Nuclear charge distribution for electromagneti-cally exited fission inside the active target.Figure 2: Distribution of the residuals for tracking of frag-ments inside the right compartment of the TwinMUSIC.The resolutions given are deduced for single anodes.Figure 3: Position resolution obtained for the tracking offragments inside the TwinMUSIC.GSI SCIENTIFIC REPORT 2013 FG-S-FRS-10doi:10.15120/GR-2014-1-FG-S-FRS-10 345

Characterizing the SOFIA/ANDES TwinMUSIC

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Characterizing the SOFIA/ANDES TwinMUSIC

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