MASHAs tale: Determination of masses and nuclear physical properties of heavy and superheavy elements using MASHA spectrometer Directed by: Luboš Krupa Starring: Kostadin Zashev (BG) Antonín Opíchal (CZ) MASHA group Robert Poenaru (RO) Josef Havlík (CZ) Flerov Laboratory of Nuclear Reactions Petr Štaffa (CZ) JINR, Dubna, Russia Lukáš Kouřil (CZ )
MASHA main capabilities • The mass identification of super heavy elements. • Measure the mass of synthesized super heavy elements. • Detect the alpha and beta decay of synthesized super heavy elements . • Detect spontaneous fission of synthesized super heavy elements. • To define the efficiency and operation speed of the given technique and relative yields of isotopes in the test reactions.
MASHA SETUP General ion-optical parameters: Range of energy variation, kV 15-40 Range of Br variation, Tm 0.08-0.5 The proposed setup is a combination Mass acceptance, % +/-2.8 of the so-called ISOL method of Angular acceptance, mrad +/-14 synthesis and separation of Diameter the ion source exit hole, mm 5.0 radioactive nuclei with the classical Horizontal magnification at F1/F2 0.39/0.68 method of mass analysis, allowing Mass dispersion at F1/F2, mm/% 1.5/39.0 mass identification of the synthesized Linear mass resolution at F1 75 nuclides in the wide mass range. 1300 Mass resolution at F2
MASHA main components Focal plane silicon multi strip detector Material of the catcher – flexible graphite Operating temperature of hot catcher – 1800-2000 о С Delivery time of nuclides to the ECR ion source ~ 2 s ECR Hot catcher Target Beam line Hot catcher ion source (graphite) Heater Target Heavy ion 1 12, 114 ECR beam TO Separating foil Recoil transport
Controlling and monitoring system of MASHA • made in LabVIEW (graphical programming enviroment) • using the principle called “Virtual Instrumentation“ (complicated hardware is replaced by software) • Virtual Instruments (VI) are programs, which are built in LabVIEW • user interface looks like real instruments with switches, knobs, signalization, indicators etc. Each VI consists of 2 main parts: 1) Front Panel (user interface) 2) Block diagram (graphical code)
Advantages of LabVIEW • very easy to analyze some graphical shapes, compared with structural text code • so LabVIEW is: - easy to learn - good for communication between developers and engineers - clear for application building • specialization for physical experiments and automation • easy to realize communication with instruments via serial interface, USB, GPIB, LAN (LXI), ... • signal proccesing and analyzing • colour resolution of various data types
Control application for MASHA
Controlling the power supply • communication via RS-485 using device to create virtual COM ports • low level functions from VISA palette (inicialization, read, write, etc.) • non-standard commands according communication protocol of voltage supply: U1 - to set voltage, with value (eg. U1300 to set 300 V) I1 - to read current value ( μ A)
Communication with the oscilloscope • communication via USB 2.0 • a lot of instruments drivers are available at official national instrument webpage: www.ni.com • downloading these drivers could save a lot of time • drivers (higher level functions) consist of basic function (low level functions)
Data analysis The synthesis of mercury and radon isotopes was carried out in the following reactions: 40 Ar + 144 Sm → 184-xn Hg + xn, 40 Ar + 166 Er → 206-xn Rn + xn The first step is to detect alpha decay of Hg isotopes in the focal plane of spectrometer obtained in the fusion - evaporation residue reactions. Because the 112 element is a chemical analog to mercury it would be a very good test of the whole method. The same process of fusion-evaporation residue reactions is used for Rn isotopes (The chemical properties of 114 are between Hg and inert gases).
Production of Hg isotopes In the 40 Ar + nat Sm experiment the target width was 0,63 mg · cm -2 (in terms of Sm) and the beam energy of 40 Ar in the half thickness of the target was between 142-202 MeV. The total beam dose passed through the target was 3,7 · 10 17 ions. Production of Rn isotopes Radon isotopes were produced in the fusion evaporation residue reactions 40 Ar + 166 Er at the beam energies between 147-196 MeV. The target thickness was 0,67 mg · cm -2 (in terms of Er), isotopic purity of the target was 98%.
The synthesis of 184 Hg and 204 Rn isotopes → 184 Hg 40 Ar + 144 Sm 184 Hg (30,6 s) → 182 Au (15,6 s) Beta decay (98,89%) → 180 Pt (52 s) Alpha decay (1,11%) 40 Ar + 166 Er → 204 Rn + 2n 204 Rn (1,17 min) → 200 Po (15,6 s) Alpha decay (73%) → 204 At (52 s) Beta decay (27%)
40 Ar + 144 Sm, E beam = 240 MeV, T catch = 1600 o C 40 Ar+Sm, E beam = 240 MeV 180 Hg (2.56s) 6.8 181 Hg (3.6s) 2.000 6.6 184 Hg (30.6s) 6.000 182 Hg (10.8s) 6.4 10.00 183 Hg (8.8s) 185 Hg (21s, 49s) 6.2 14.00 186 Hg (1.4m) 18.00 Energy [ MeV ] 6.0 22.00 5.8 26.00 5.6 30.00 5.4 34.00 38.00 5.2 42.00 5.0 46.00 4.8 50.00 4.6 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 Strip
Energy spectrum of alpha particles for mass number A=182 and A=202 A=203 A=204
Conclusion The isotopes of Hg and Rn were produced in the fusion-evaporation residue reactions 40 Ar + nat Sm and 40 Ar + 166 Er. Their chemical properties (adsorption energy on the surface) are close to those of 112 and 114. The spectra of alpha particles after decay of isotopes in the focal plane were measured by silicon well-type detector. The operation speed of the setup was estimated ≤ 4 seconds. The obtained results indicate that these achieved parameters of mass- spectrometer “MASHA” are close to designed values.
Island of stability
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