Beliuskina, O.

Heinz, C.

Heinz, S.

Kozhuharov, C.

Pomorski, M.

Träger, M.

GSI Repository

Diamond dE-E-ToF-telescope for heavy ion reactions at the Coulomb barrier∗O. Beliuskina†1, C. Heinz2, S. Heinz1, C. Kozhuharov1, M. Pomorski3, and M. Tra¨ger11GSI, Darmstadt, Germany; 2JLU, Giessen, Germany; 3CEA-LIST, Saclay, FranceTarget of our interest is the study of heavy ion reactions,such as multinucleon transfer, quasi-fission and/or fusion-fission, at energies close to the Coulomb barrier as well astheir possible application for the synthesis of new isotopes,especially in the high-Z neutron-rich region.The conventional time-of-flight technique, combinedwith the dE-E method, allows us (in general) to identify themass and the charge of the reaction products and to studythe reaction kinematics. Nonetheless, studying heavy par-ticles at low energies needs a special approach. There aresome limitations: pulse hight defect, radiation hardness,etc. Moreover, heavy ions at low energy have very shortranges, which means that we have to find a very thin detec-tor capable of measuring energy loss and time simultane-ously.Due to their unique properties (a good energy resolu-tion comparable to silicon detectors, e.g. ∆E=20keV foralphas; time resolution on the order of few ten ps due tovery high electron and hole mobilities, high count rate upto 109 due to very short rise and fall times (∼20ps) andhigh radiation hardness[1]) diamonds are good candidatesfor this application. Very recently, Pomorski et al. suc-ceeded in fabricating ultra-thin diamond membranes withonly few micrometers thickness that are able to measureenergy loss and produce simultaneously time signals withexcellent resolution[2].Based on these findings we initiated a program to inves-tigate single crystal (sc) diamond detectors for identifica-tion of low-energy heavy ion reaction products. For thisapplication we realized the very first dE-E-ToF telescope[3] which consists of 2 sc diamond detectors: ”dE/Start“and ”E/Stop“. First measurements were carried out with amixed nuclide α-source. The diamond ”dE/Start“-detectorhad a thickness of ∼4 µm and the diamond ”E/Stop“-detector ∼50 µm. The distance between the detectors was14 mm. In Fig. 1a-1c the obtained result is shown. Fig.1a shows the two-dimensional dE versus residual energyEr spectrum measured with the mixed nuclide α-source.There are three well separated ridges which correspond tothe three α-lines. Fig 1b shows the one-dimensional energyspectrum where line 1 is the energy loss in the membranedetector, line 2 is the residual energy measured in the stopdetector and line 3 is the sum of dE and Er for each event.Fig. 1c shows the time of flight spectrum.Furthermore, we applied the diamond dE-E-ToF tele-scope to study reaction products from collisions of∗Work supported by FAIR@GSI PSP code:500457† o.beliuskina@gsi.de dE, keVEt, channela)Et, keVMixed nuclide (Pu,Am,Cm)sourceEr, keV2000 4000 600004080b)Counts32Counts10,0 0,5 1,0 1,5 2,0 2,5 3,00400800t, nsc)  ToF Gaussianxc = 0,96 ns= 0,21 nsfwhm = 0,42 nst1line=1,29 nst2line=1,24 nst3line=1,19 ns200 400 600300600900 d) 36S(160MeV)+186WdE, channelFigure 1: a) dE versus Er spectrum of α-particles measuredwith diamond detectors b) Energy spectrum of α particlesc) Time of flight spectrum of α-particles d) dE versus Erspectrum measured in 36S+186W reactions at 160 MeV.36S+186W at a beam energy of 160 MeV. The experimentwas carried out at JINR Dubna where we installed the di-amond dE-E-ToF telescope together with the CORSET-setup [4] which will be subject of a different report. Fig-ure 1d shows the two-dimensional dE versus E spectrum ofreaction products from S+W measured with the diamonddetectors. The most intensive ridge corresponds to elasti-cally scattered sulfur which passes through the membraneand loses about 20 MeV. The intensity of the elasticallyscattered W is 150 times lower than of S at the chosen de-tection angle of 20 degrees. Therefore, the W line is notvisible in the spectrum.Our first results are very encouraging and show that weare on the right track by utilizing ultra-thin sc diamond de-tectors as ”dE/Start“ combined with sc diamond stop coun-ters for the A and Z identification of reaction products at theCoulomb barrier. Further studies are anticipated aiming atimproved time and energy resolutions, radiation hardness,pulse hight defects, etc.References[1] E. Berdermann et al., Proc. of the XXXVI Intern. WinterMeeting on Nucl. Physics, Bormio 1998[2] M. Pomorski et al., Applied physics letters 103, 112106(2013)[3] O. Beliuskina, 2nd ADAMAS Workshop, GSI, DarmstadtDecember, 2013, http://www-adamas.gsi.de[4] E. M. Kozulin et al., Instruments and Experimental Tech-niques 51, 44 (2008)GSI SCIENTIFIC REPORT 2013 NUSTAR-SHE-07doi:10.15120/GR-2014-1-NUSTAR-SHE-07 FAIR@GSI 131

Diamond dE-E-ToF-telescope for heavy ion reactions at the Coulomb barrier

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Diamond dE-E-ToF-telescope for heavy ion reactions at the Coulomb barrier

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