Mass Determination of Rn and Hg isotopes using MASHA

Transcription

1 Mass Determination of Rn and Hg isotopes using MASHA Alfred M. Sehone Lumkile Msebi Oleg Lishyk Stanislav Stanishevski Yuliya Brechko Supervisor Krupa Lubosh Flerov Laboratory of Nuclear reactions, JINR, Dubna, Russia

2 Introduction (Lumkile Msebi) MASHA SETUP MEDIPIX Detector Mass Determination of Hg isotopes Mass Determination of Rn isotopes Conclusion 1

3 The main aims Studying of MASHA main capabilities The use of MEDIPIX for the detection of alpha and beta energies To determine the energy of alpha decay of Hg and Rn isotopes produced in the fusion reactions: 40 Ar + nat Sm nat-xn Hg + xn 40 Ar Er 206-xn Rn + xn 2

4 Introduction 3 One of the remarkable scientific achievements in the last decade was the discovery of super heavy elements with Z= and neutron rich isotopes with Z= The fusion of new nuclides stimulated interest in finding methods of identifying super heavy elements. Measurement of the mass of new nuclides have to be carried out online and it is for this reason that MASHA was designed. MASHA has a unique ability to measure the mass synthesized super heavy elements and the same time to detect their alpha decay and spontaneous fission

5 Introduction It is possible to use test experiments to simulate conditions that are close to real experiments for measurement of the mass of super heavy elements. The following fusion evaporation reaction was done: 40 Ar + nat Sm nat-xn Hg + xn 40 Ar Er 206-xn Rn + xn 4

6 Introduction MASHA SETUP (Julia Brechko) MEDIPIX Detector Mass Determination of Hg isotopes Mass Determination of Rn isotopes Conclusion 5

7 MASHA main capabilities Measure the mass of synthesized super heavy elements Detect alpha and beta decay of synthesized super heavy elements Detect spontaneous fission of synthesized super heavy elements Determine the operation speed of the technique Determine the relative yields of isotopes 6

8 MASHA SETUP 7 General ion-optical parameters: Range of energy variation, kev Range of Br variation, Tm Mass acceptance, % +/-2.8 Angular acceptance, mrad +/-14 Diameter the ion source exit hole, mm 5.0 Horizontal magnification at F1/F2 0.39/0.68 Mass dispersion at F1/F2, mm/% 1.5/39.0 Linear mass resolution at F1 75 In the source atoms are being ionized, accelerated and formed the beam which is being separated by magneto-optical system of the mass-spectrometer. The source allows to obtain the ion beam consisting of almost 100% of singly ionized atoms and efficiency of ionization for noble

9 ECR ion source Hot catcher scheme Hot catcher Target Beam line Recoil transport The target have honeycombed structure with transparence 85%. The products of nuclear reactions leave the target, go through the MF and stop in graphite absorber which is getting warm up to K. Then, products of nuclear reactions in the form of atoms diffuse from the GA and get to 8 the ECR ion source.

10 Silicon multi strip detector 9 The detector assembly allows to detect no less than 90% of alpha particles emitted in the first nucleus decay, taking place in the center of frontal part of detector. Configuration well type Number of the focal strips 192 (step 1.25 mm) Number of the back side strips 160 (step 5 mm)

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12 Introduction MASHA SETUP MEDIPIX Detector (Alfred M. Sehone) Mass Determination of Hg isotopes Mass Determination of Rn isotopes Conclusion 11

13 MEDIPIX Detector Principle of hybrid pixel detectors 12 p-substrate p+ I in Charged particle n- g m n-well V out Semiconductor detector Bump-bond contact ASIC The sensor chip (top) is bumpbonded to the readout ASIC (bottom). Hybrid technology allows for the use of different semiconductor sensors (e.g, Si, CdTe, GaAs). Photons detection - indirect transfer of energy to charged particles through photoelectric effect, Compton scattering and pair creation. Pulse processing is simultaneously fast and noise

14 MEDIPIX Detector 13 A digital CMOS imaging chip which emerged from particle detection in high energy physics experiments, designed at CERN in the microelectronics group. The chip forms a hybrid photon counting detector with the active medium (semiconductor detector) bump-bonded to the electronics (ASIC). This provides direct charge conversion of photons and therefore minimum image blurring. Single photon semiconductor pixel hybrid detector (no photon, no signal = no noise for longer counting periods)

15 Schematic View Medipix2 device is composed of 300μm silicon detector Dead layer between 200 and 500nm square pixels each one of 55μm side Measurement Modes Medipix mode Counting of incoming particles Timepix Particle interaction per arrival time Time-Over-Threshold - Direct measurement 14 of energy in each pixel USB Readout Interface

16 Integrated with the MASHA 15

17 Properties of MEDIPIX 16 Medipix2 will record an event in one or several pixels if the energy deposited by an incoming particle is greater than the threshold energy (> 5 kev). It is a vacuum operated device and requires no cooling The minimal dead layer ensures high resolution, high resolving pixel-read-out and maximises detection efficiency Pixelman software - Pattern recognition of charged or neutral particles

18 Introduction MASHA SETUP MEDIPIX Detector Mass Determination of Hg isotopes (Stanislav Stanishevski) Mass Determination of Rn isotopes Conclusion 17

19 Why do we study mercury? Element 112 is a representative of Group 12 of the Periodic Table. The chemical properties of this element are similar to those of its lighter homologue mercury. Element 112 was found to be very volatile like mercury. 18

20 40 Ar + nat Sm nat-xn Hg + xn 180 Hg 176 Pt + 4 He Mercury atoms undergo α- decay giving appropriate isotopes of platinum. 181 Hg 177 Pt + 4 He 19 -particles from platinum decays can be also detected using the strip detector.

21 Energy spectra for Hg isotope 184 β Hg Tl 20

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23 Introduction MASHA SETUP MEDIPIX Detector Mass Determination of Hg isotopes Mass Determination of Rn isotopes (Oleg Lishyk) 22 Conclusion

24 Mass Determination of Rn isotopes Rn is a chemical analog of the 114 element. The synthesis of Rn isotopes was carried out in the reaction: 40 Ar Er 206-xn Rn + xn The products of fusion-evaporation residue reaction were detected by silicone detector in the focal plane 23

25 40 Ar Er, Gate on mass A = Ar Er, Gate on mass A = Ar Er, Gate on mass A = Ar Er, Gate on mass A =

26 40 Ar Er, Gate on mass A = 205 And after proceeding and analyzing data, after many sleepless nights we obtained two dimensional matrix as a function of α particles of Rn isotopes and strip number! 25

27 26 40 Ar+ 166 Er, E beam = 198 MeV, T catcher =1600 o C

28 Introduction MASHA SETUP MEDIPIX Detector Mass Determination of Hg isotopes Mass Determination of Rn isotopes Conclusion (Lumkile Msebi) 27

29 Conclusion We were able to determine the energies of the alpha decay obtain from fusion evaporation residue reaction. The mass of different isotopes of Hg and Rn were found. Energies of decay products such as Pt and Tl in the case of mercury and in the case of radon, we found energies of Po and At. The results obtained show that the achieved parameters of MASHA are close to the real values. 28

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