SYNTHESIS OF SUPERHEAVY ELEMENTS USING THE MASS SPECTROMETER MASHA Students Timofei Tikhomirov - RB Kevin Li - RSA Alesya Lebedevich - RB Maurice Mashau - RSA Supervisor Krupa Lubosh Flerov Laboratiory of Nuclear Reactions, JINR, Dubna, Russia
The main purposes *To measure the alpha decay of Hg and Rn isotopes, produced in fusion reactions: 40 Ar+ nat Sm nat-xn Hg+xn and 40 Ar+ 166 Er 166-xn Rn+xn, in the focal plane of mass spectrometer. *To define the operation speed of the given technique and relative yields of isotopes in the test reactions. *To analyse data acquired from the Medipix2 data and simulate the detector to reproduce some results. *To implement positional tracking alongside energy deposition.
(Mass Separator of Heavy Atoms) Mass measurements with accuracy ~ 10-7 -spectroscopy of transuranium nuclei -spectroscopy X-ray spectroscopy Laser spectroscopy
1 2 3 4 Пучок ионов 1 Target box with hot catcher; 2 Ion source; 3 Mass separator; 4 Detector in the focal plane D1 Q1 Q2 D2 General ion-optical parameters: Range of energy variation, kv 15-40 Range of Br variation, Tm 0.08-0.5 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 Mass resolution at F2 1300 Q3 S1 D3a D3b S2 Mass-spectrometer MASHA at the beam line of the cyclotron U-400M The proposed setup is a combination of the so-called ISOL method of synthesis and separation of radioactive nuclei with the classical method of mass analysis, allowing mass identification of the synthesized nuclides in the wide mass range.
Testing experiments on heavy ion beams 112 element chemical analog of Hg 114 element chemical analog of Rn
Energy of alppha decay [ MeV ] 40 Ar+ 166 Er, E beam = 198 MeV, T catcher =1600 o C 7,6 7,4 7,2 7,0 6,8 6,6 6,4 6,2 6,0 5,8 5,6 5,4 201 Rn (3.8s, 7s) 202 Rn (9.85s) 203 Rn (28s, 45s) 204 Rn (1.24m) 205 Rn (2.83m) counts 2,000 27,00 52,00 77,00 102,0 127,0 152,0 177,0 200,0 5,2 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 Strip number
counts counts counts counts 2200 2000 197 Po (E kev) 40 Ar + 166 Er, Gate on mass A = 201 201 Rn (E kev) 2500 198 Po (E kev) 40 Ar + 166 Er, Gate on mass A = 202 201 Rn (E kev) 1800 1600 E kev 2000 E kev 1400 1200 1000 E kev E kev 1500 800 1000 E kev 600 400 200 E kev 500 0 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 energy [ kev ] 0 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 energy [ kev ] 800 700 600 199 Po (E kev) 40 Ar + 166 Er, Gate on mass A = 203 E 203 Rn (E kev) kev 260 200 Po (E kev) 240 220 200 40 Ar + 166 Er, Gate on mass A = 204 E kev 204 Rn (E kev) 500 180 160 400 140 300 E kev 120 100 200 100 E E kev kev 0 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 energy [ kev ] 80 60 40 20 E kev 0 5200 5400 5600 5800 6000 6200 6400 6600 6800 7000 7200 7400 energy [ kev ]
Log10(Po isotopes yield) Log10(Rn isotopes yield) Yields of Rn 5 Yield 4,8 4,6 Beam energy of 40 Ar = 202 MeV 4,4 4,2 4 3,8 3,6 3,4 Yields of Po 3,2 3 202 203 204 205 Mass number, a.m.u. 5,2 5 Yield 4,8 4,6 4,4 4,2 4 3,8 3,6 197 198 199 200 201 Mass number, a.m.u.
Log10(Pt isotopes yield) Log10(Hg isotopes yield) Yields of Hg Yield 7 6,5 6 Beam energy of 40 Ar = 202 MeV 5,5 5 4,5 Yields of Pt 4 3,5 180 181 182 183 184 185 Mass number, a.m.u. 6,5 6 Yield 5,5 5 4,5 4 3,5 176 177 178 179 180 181 Mass number, a.m.u.
Semiconductor single photon pixel hybrid detector MEDIPIX Detector chip Medipix-2 chip Bump-bonding Planar (300, 700, 1000 m thick) silicon pixel detector (also GaAs, CdTe, or n converter) Bump-bonded to Medipix readout chip containing amplifier, discriminator and counter for each pixel.
Medipix2 device is composed of 300µm silicon detector It has the dead layer region which is roughly between 200nm and 500nm 256 256 square pixels each one of 55µm side Medipix mode - Counting of incoming particles Timepix mode - Measurement of particle interaction per arrival time Time over threshold (TOT) Direct measurement in each pixel Medipix2 device will record an event in one or several pixels if the energy deposited by an incoming particle is greater than the threshold energy (>5kev).
Radium 224 Radon 220 Polonium 216 Lead 212 Bismuth 212 Thallium 208 Polonium 212 Lead 208
Beta spectrum Alpha spectrum Double alpha spectrum
Actual Energy of Emitted Beta-particles For beta decay, the energy distribution for betaparticles is The energy efficiency of the detector highly dependent upon detector geometry. The Medipix2 detector registers a maximal count at an energy of approximately 120 kev. We have qualitatively reproduced the detector response from a previous GEANT4 simulation from a current Phd student at JINR (shown below). Detector Response from Emitted Beta-particles
Actual Energy of Emitted Beta-particles Detector Response from Emitted Beta-particles
We observe that there are discretized energy peaks that protrude from the otherwise continuous measured energy distribution of beta-particles. After consultation with our supervisor, we hypothesize that this is the result of internal conversion electrons, which would explain the energy discretization.
Position (x, y) versus Energy Deposition Spectra from data 229 Rn 230 Rn 231 Rn 232 Rn
Simulation of Position versus Energy Deposition
Simulation of Position versus Energy Deposition
- Our Supervisor Dr Lubos Krupa and the MASHA team - I. cěk and Hein Fourie