opportunities to study the she production mechanism...
TRANSCRIPT
TAMU SHE 2015 Slide 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 2
Outline
• Intro – Fusion with RIBs
• ReA3 Facility @ NSCL
• What can we do NOW with RIBs?
• Coincident Fission Fragment Detector
• Summary
• AcknowledgementsNSCL
TAMU SHE 2015 Slide 3
Motivation
New n-rich superheavy isotopes
1. Access long lifetimes
2. Fill in the n-rich gaps
3. Extended studies of N=162
4. New mass measurements?
5. Understand how to approach
N=184?
TAMU SHE 2015 Slide 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 5
Fusion with RIBs
Light Nuclei:6,8He, 9,11Li, 10,11Be, 8B, 10,11,14,15C, 17F, 20O
- Enhancement/hindrance due to
halo and weakly bound nuclei
- Astrophysics
TAMU SHE 2015 Slide 6
Fusion with RIBs
Light Nuclei:6,8He, 9,11Li, 10,11Be, 8B, 10,11,14,15C, 17F, 20O
HRIBF: 132,128,126Sn + 58,56Ni132Sn + 40,48Ca132Sn + 96Zr132Sn + 100Mo134Te + 40Ca
- Extreme neutron excess
- Sub-barrier transfer couplings
- Hindrance with n-rich RIBs
TAMU SHE 2015 Slide 7
Fusion with RIBs
“Fast beams”38S + 181Ta, 208Pb (NSCL)29,31Al + 197Au (RIKEN)
Light Nuclei:6,8He, 9,11Li, 10,11Be, 8B, 10,11,14,15C, 17F, 20O
HRIBF: 132,128,126Sn + 58,56Ni132Sn + 40,48Ca132Sn + 96Zr 132Sn + 100Mo134Te + 40Ca
SHE relevant hot and cold
fusion reactions require
medium-mass RIBs.
TAMU SHE 2015 Slide 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 9
Where can we study SHE synthesis with RIBs?
NSCL has been a “fast” fragmentation facility (RIBs @ 50-150 MeV/u)
We want those same RIBs at lower energies (from thermal to Coulomb barrier)
for studying nuclear reactions, structure, and astrophysics.
Facilities currently offer low-energy RIBs:
ISAC-TRIUMF, SPIRAL, HIE-ISOLDE, CARIBU-ARIES-ANL, …, HRIBF
ReA3 represents a new concept of stopping and re-accelerating fast
fragmentation beams.
Projectile Fragmentation
TAMU SHE 2015 Slide 10
ReA @ NSCL
ReA
experimental areaEBIT Charge Breeder
gas stopping area
1. Produce RIB at NSCL
2. Thermalize beam in gas stopper
3. Charge breed isotope
4. Re-accelerate
1
2
34
RIBs with stable beam characteristics
TAMU SHE 2015 Slide 11
ReA @ NSCL
NSCL PAC38 accepted proposals at ReA3
NSCL PAC39 reviewing new proposals for ReA3
Beams include 47-37K, 46-34Ar, 40-30S
• Technique provides any beam that can be produced by projectile fragmentation
• Chemistry independent (compared to ISOL)
• Short development time for new beams.
MeV
/u
TAMU SHE 2015 Slide 12
ReA @ NSCL – Beam Intensities
Current Facility: NSCL + ReA
104-105 pps near stability
Example: 39-41K stable, 37K 8e3 pps, 46K 5e4 pps, 47K 3e4 pps
Future Facility: FRIB + ReA
Fast beam rates
1e10 pps
1e12 pps
TAMU SHE 2015 Slide 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 14
Coincident Fission Fragment Detector
• Experimental program to study PCN
and scap 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.
beam
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 Silicon
monitors
PPACS
TAMU SHE 2015 Slide 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: 46K + 208Pb
TAMU SHE 2015 Slide 16
Experimental Devices
Active Target Time Projection Chamber
10Be+4He
W. Mittig, D. Bazin, W.G. Lynch
Collaborators: LBNL, LLNL, ND, WMU, SMU
• Low intensity experiments (~100 pps)
• 4p efficiency
• dE/dX, E, Br, range, 3-D tracking
•Active or stationary target
• Max intensity ~2-5 * 104 pps
• Prototype TPC successfully commissioned
•Applicable for fusion/fission/breakup studies.
Large volume 100 cm x φ60 cm 0.2 to 1 atm gas pressure
High granularity 10,000 pads, ~5 x 5 mm2
Bρ analysis Solenoid 2T
a
a
a
TAMU SHE 2015 Slide 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…