1. STATUS REPORT ON THE “MASHA” SET-UP A.M.Rodin, A.V.Belozerov, S.N.Dmitriev, Yu.Ts.Oganessian, R.N.Sagaidak, V.S.Salamatin, S.V.Stepantsov, D.V.Vanin PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

2. Introduction Status of the mass-spectrometer MASHA From ISOL technique to gas catcher Future PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

3. Introduction MA ss S eparator of H eavy A toms 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. General ion-optical parameters Range of energy variation, kV15-40 Range of Br variation, Tm0.08-0.5 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 F175 Mass resolution at F2 1150 PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

4. Introduction Chemistry of the element 112 PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

5. First experiments: Mass identification of 112 и 114 elements synthesized at the reactions 242 Pu( 48 Ca,3n) 287 114(0.5 s, a) –> 283 112(4 s, a 9.95 MeV) 244 Pu( 48 Ca,3-4n) 289 114 (2.7 s, a 9.82 MeV) –> 283 112(4 s, a 9.95 MeV) Mass identification of 113 elements synthesized at the reaction 243 Am( 48 Ca,3n) 288 115 (80 ms, a 10.5 MeV ) -> 284 113(0.5 s, a 10.0 MeV, (analog of Tallium) Status of the mass-spectrometer MASHA PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

6. Mass-spectrometer MASHA at the beam line of the cyclotron U-400M New beam line with low energy of the U-400M was built Mass-spectrometer mounted at the new beam line Hot catcher is ready Focal plane detector system is ready Start of test and first experiments – April of 2010 Status of the mass-spectrometer MASHA PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

7. Status of the mass-spectrometer MASHA Mass spectrum of Kr isotopes: Total efficiency – 47% Mass resolution - 1400 Mass measurement accuracy – 1.3 x 10 -5 PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

8. Main parameters of gas catcher Operating gas – He purity <0,1 ppm. Operating pressure into gas cell – 100 mbar. Extraction time – 10 ms. Efficiency 10-40%. Beam emittance ~1.0 . mm. mrad From ISOL technique to gas catcher PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

9. Ideal gas stopper Short extraction times. Extraction times of 10 ms or less would be ideal. Big enough efficiency. Not less than 20%. Handling of high beam intensities. The facility should provide secondary beam intensities of up to 10 9 s -1. Applicability to all fragment beams. Universality. From ISOL technique to gas catcher PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

10. ParameterECR ion source Gas catcher Range of energy variation, kV15-40 Range of Bρ variation, Tm0.08-0.5 Mass acceptance, %2.8 Angular spread, mrad145 Diameter the ion source exit hole, mm5.01.0 Horizontal magnification at F 1 /F 2 0.39/0.680.24/0.90 Vertical magnification at F 1 /F 2 2.40/3.138.75/1.25 Mass dispersion at F 1 /F 2, mm/%1.5/39.0 Linear mass resolution at F 1 75420 Mass resolution at F 2 1150 5700 General ion-optical parameters of MASHA From ISOL technique to gas catcher PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

11. Observation of beam rate-dependent efficiencies as a function of the ionization rate in gas stopping systems at MSU, RIKEN, GSI/SHIPTRAP, LISOL/Leuven, and ANL. ~10 7 c -1 of 48 Ca (6 MeV/n) From ISOL technique to gas catcher PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

12. Magnet: Bρmax = 2.7 Tm B 0 max = 6.0 T Banding angle = 82.4 o Rcentre ray = 45.2 cm Centre ray length = 65 cm Pole gap, 2h = 10 cm Beam horizontal working region = ±10 cm Entrance (exit) pole tilt angle = 30 o (14.7 o ) Separator characteristics: Target – magnet distance = 1.0 m Magnet – catcher entrance distance = 1.0 m Solid angle = 10.0 msr Θ X = ± 4.6 o, Θ Y = ± 2.3 o ∆P/P (full) = 4.5% Focal plane dispersion = 2.7 cm/%Bρ Gas – H 2 at the pressure 1-5 mbar Gas-filled recoil separator From ISOL technique to gas catcher PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

13. Reaction: 48 Ca + 238 U → 286 112* → 283 112 + 3n Target: backing foil Ti(0.75 mg/cm2) + UF4 (0.4 mg/cm2) Beam: E 0 ( 48 Ca) = 234 MeV (4.88 MeV/n) diameter on target = 10 mm ε X = ε Y = 30π mm mrad (r.m.s) ∆E/E 0 = ± 0.5% (r.m.s) Total transmission – 65% Simulation for SHE From ISOL technique to gas catcher PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

14. Experimental facility for very heavy nuclei research From ISOL technique to gas catcher PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

15. Future Methodic development Gas catcher and gas-filled recoil separator New design of the silicon detectors DSD with 0.1 mm strips Germanium detectors for Z identification New electronics and data acquisition Start detector based on electron emission from silicon PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010

16. Future Experimental research Mass identification of heaviest nuclides Mass measurements of heavy nuclides with accuracy up to 10 -7 Decay spectroscopy of neutron deficit and neutron rich nuclides with A and Z identification Synthesis and decay research of new neutron rich nuclides Collinear laser spectroscopy at the wide area of the nuclide chard PAC for Nuclear Physics, 31 st meeting, 25-25 January 2010