Opportunities to study the SHE production mechanism with rare isotopes at the ReA3 facility

Transcription

1 Opportunities to study the SHE production mechanism with rare isotopes at the ReA3 facility Zach Kohley National Superconducting Cyclotron Laboratory Department of Chemistry Michigan State University, E. Lansing, MI International Symposium Super Heavy Nuclei Texas A&M University, College Station, TX March 31-April 2, 2015 TAMU SHE 2015 Slide 1

2 Outline Intro Fusion with RIBs ReA3 NSCL What can we do NOW with RIBs? Coincident Fission Fragment Detector Summary Acknowledgements NSCL TAMU SHE 2015 Slide 2

3 Motivation New n-rich superheavy isotopes 1. Access long lifetimes 2. Fill in the n-rich gaps 3. Extended studies of N= New mass measurements? 5. Understand how to approach N=184? TAMU SHE 2015 Slide 3

4 Motivation Has always has been intriguing to consider the use of n-rich RIBs for SHE synthesis. What has been done, experimentally, so far? TAMU SHE 2015 Slide 4

5 Fusion with RIBs - Enhancement/hindrance due to halo and weakly bound nuclei - Astrophysics Light Nuclei: 6,8 He, 9,11 Li, 10,11 Be, 8 B, 10,11,14,15 C, 17 F, 20 O TAMU SHE 2015 Slide 5

6 Fusion with RIBs - Extreme neutron excess - Sub-barrier transfer couplings - Hindrance with n-rich RIBs HRIBF: 132,128,126 Sn + 58,56 Ni 132 Sn + 40,48 Ca 132 Sn + 96 Zr 132 Sn Mo 134 Te + 40 Ca Light Nuclei: 6,8 He, 9,11 Li, 10,11 Be, 8 B, 10,11,14,15 C, 17 F, 20 O TAMU SHE 2015 Slide 6

7 Fusion with RIBs Light Nuclei: 6,8 He, 9,11 Li, 10,11 Be, 8 B, 10,11,14,15 C, 17 F, 20 O Fast beams 38 S Ta, 208 Pb (NSCL) 29,31 Al Au (RIKEN) SHE relevant hot and cold fusion reactions require medium-mass RIBs. HRIBF: 132,128,126 Sn + 58,56 Ni 132 Sn + 40,48 Ca 132 Sn + 96 Zr 132 Sn Mo 134 Te + 40 Ca TAMU SHE 2015 Slide 7

8 Motivation Q: What has been done, experimentally, so far? A: Not much 3 RIB experiments under difficult conditions Q:Why? A: (Opinion) Very few facilities with medium-mass RIBs at appropriate energies. TAMU SHE 2015 Slide 8

9 Where can we study SHE synthesis with RIBs? Facilities currently offer low-energy RIBs: ISAC-TRIUMF, SPIRAL, HIE-ISOLDE, CARIBU-ARIES-ANL,, HRIBF NSCL has been a fast fragmentation facility MeV/u) Projectile Fragmentation We want those same RIBs at lower energies (from thermal to Coulomb barrier) for studying nuclear reactions, structure, and astrophysics. ReA3 represents a new concept of stopping and re-accelerating fast fragmentation beams. TAMU SHE 2015 Slide 9

10 NSCL RIBs with stable beam characteristics 3 EBIT Charge Breeder 4 ReA experimental area 2 gas stopping area 1. Produce RIB at NSCL 2. Thermalize beam in gas stopper 3. Charge breed isotope 4. Re-accelerate TAMU SHE 2015 Slide 10 1

11 MeV/u NSCL Technique provides any beam that can be produced by projectile fragmentation Chemistry independent (compared to ISOL) Short development time for new beams. NSCL PAC38 accepted proposals at ReA3 NSCL PAC39 reviewing new proposals for ReA3 Beams include K, Ar, S TAMU SHE 2015 Slide 11

12 NSCL Beam Intensities Current Facility: NSCL + ReA pps near stability Example: K stable, 37 K 8e3 pps, 46 K 5e4 pps, 47 K 3e4 pps Future Facility: FRIB + ReA Fast beam rates 1e12 pps 1e10 pps TAMU SHE 2015 Slide 12

13 Big Picture for ReA Applicability of RIBs for SHE production: - Will new SHEs be produced at NSCL/ReA3? No - Will new SHEs be produced at FRIB/ReA? VERY unlikely - Can new isotopes of SHE s be produced at FRIB/ReA? Possibly What can we do NOW at NSCL/ReA? Study SHE reaction mechanism using neutron- and proton-rich RIBs TAMU SHE 2015 Slide 13

14 Coincident Fission Fragment Detector Experimental program to study P CN and s cap with RIBs at ReA3. 4 large area PPACs (30cm x 40cm) 2V method for fission fragment mass 30-45% coincidence efficiency Large angular coverage Versatile device for stable and radioactive beam experiments. Goals: Define the most promising experiments at FRIB for production of new neutron-rich isotopes of SHEs. Understand how or if the fusion process is modified with the use of neutron-rich RIBs. MCP beam PPACS Silicon monitors TAMU SHE 2015 Slide 14

15 Coincident Fission Fragment Detector Status (aka when will this happen!): Device is completed final tests of PPACs and MCPs with digital electronics (XIA pixie systems) Approved PAC38 experiment hopefully run in Fall 2015: 46 K Pb TAMU SHE 2015 Slide 15

16 Experimental Devices Active Target Time Projection Chamber W. Mittig, D. Bazin, W.G. Lynch Collaborators: LBNL, LLNL, ND, WMU, SMU a 10 Be+ 4 He a a Large volume 100 cm x φ60 cm 0.2 to 1 atm gas pressure High granularity 10,000 pads, ~5 x 5 mm 2 Bρ analysis Solenoid 2T Low intensity experiments (~100 pps) 4p efficiency de/dx, E, Br, range, 3-D tracking Active or stationary target Max intensity ~2-5 * 10 4 pps Prototype TPC successfully commissioned Applicable for fusion/fission/breakup studies. TAMU SHE 2015 Slide 16

17 Summary Expect to see exciting results from low-energy structure and reactions research at ReA3! ReA3 presents unique opportunity to explore SHE relevant reactions with neutron- and proton-rich RIBs. Coincident Fission Fragment Detector constructed Need to think towards future of SHE research at FRIB. ReA6 upgrade to higher energies Spectrometer ISLA White Paper available Welcome ideas for RIB experiments, interest in fusion at ReA3 TAMU SHE 2015 Slide 17

18 Acknowledgments Kalee Hammerton (GS) Aditya Wakhle (PD) Krystin Stiefel (GS) Theoretical Support: Sait Umar Volker Oberacker John Yurkon (Det. Lab) David Hinde Nanda Dasgupta Cedric Simenel Elizabeth Williams Walt Loveland TAMU SHE 2015 Slide 18