National Superconducting Cyclotron Laboratory An...
Transcript of National Superconducting Cyclotron Laboratory An...
National Superconducting National Superconducting Cyclotron LaboratoryCyclotron LaboratoryCyclotron LaboratoryCyclotron Laboratory
An overviewAn overview
Ana D. BecerrilAna D. BecerrilNSCL and Physics and Astronomy Department, Michigan State University
Joint Institute for Nuclear Astrophysics
University of North Carolina September, 2009
Science at NSCLScience at NSCL
• Exploring the nuclear landscape• Nuclear Theory
JINA• JINA• Nuclear Astrophysics
– Accreting Neutron StarsAccreting Neutron Stars– Equation of State of Dense Matter– r-process
rp process– rp-process– Supernovae
• Accelerator Physicsy
The experimental area300 feet
S800
beam switchyard
S800spectrograph
K500 cyclotron
A1900 fragment separator
K1200cyclotron
separator
Adapted from Z. Constan, NSCL
Coupled Cyclotron Facilityp y y
Ion Sources
NSCL uses Electron NSCL uses Electron Cyclotron Resonance (ECR) sources, which trap stable atoms and ionize them h h lli i i h through collisions with
electrons, which are kept in motion by microwaves.
W h 3 ECR
magnet
We have 3 ECR sources:
•SC-ECR
•ARTEMIS
•SuSI
Adapted from Z. Constan, NSCL
The K500 Cyclotron• Year completed: 1982 (the world’s first superconducting cyclotron)• Diameter: 10 ft Weight: 100 tons
M i fi ld 3 5 T l
y
• Magnetic field: 3-5 Tesla• Superconducting wire coil: 20 miles long, carrying 800 amps• Maximum energy it can impart to a proton: 500 MeV
Adapted from Z. Constan, NSCL
The K1200 Cyclotron• Completed 1988: the world’s second-highest-
energy cyclotron
y
• Pre-accelerated ions from K500 pass through a stripper foil in the K1200, increasing ionization and improving accelerating efficiency.
l i l i h h• Nuclei leaving the K1200 can reach 0.5 c (typically 150 MeV/nucleon).
• Dees charged to 140 kV, alternated at 23 MHz.
Adapted from Z. Constan, NSCL
Fragment production and separation
86Kr
Adapted from A. Stolz, NSCL
Fragment production and separation
Adapted from A. Stolz, NSCL
Fragment production and separation
A1900 Fragment SeparatorSeparation method based on magnetic-rigidity analysis and energy-loss in degrader materials.•4 dipoles (for bending, spreading)•8 quadrupole triplets (for focusing)
Adapted from A. Stolz, NSCL
Fragment production and separation
Adapted from A. Stolz, NSCL
Fragment production and separationg p p
Adapted from A. Stolz, NSCL
Fragment production and separationg p p
The A1900 fragment separatorg p
Fragment production and separationFragment production and separation
Beams of proton rich nuclei …
Huge contamination from low momentum tails of more abundant hi h i idit f thigher rigidity fragments.
⇒ Need additional purification of secondary beam!
RF-kicker
~ 16 mThe RFFS provides purification of neutron deficient beams by time-of-flight selection
π cellQ ad polesQuadrupoles
RFkickerMatching
Cellπ/2 cell π cel
ExperimentCollimation
QuadrupolesQuadrupoles
Selection slits
M. Doleans et al., “Status Report on the NSCL RF Fragment Separator” Proc.of PAC, Albuquerque, NM, to be published (2007)
slits
•1 5m long RF ca it Vma 100kV•1.5m long RF cavity, Vmax=100kV•Beam Rejection factor of > 200 for 100Sn•First experimental campaign in Fall 2008
RF-kickerNSCL Beta Counting Station(Mantica et al.) With SeGA Ge-detectors
RF FragmentSeparator
Ge Ge-
Ge Ge
+
•The RFFS applies a uniform RF electric field at the cyclotron frequency transverse to the y ydirection of the beam.
•The various species in the beam cocktail arrive with different RF phases and experience different transverse deflections. This effectively results in a velocity-dependent selection of fragments.y p g
•Contaminants are eliminated by a set of vertical slits
RF-kickerNSCL Beta Counting Station(Mantica et al.) With SeGA Ge-detectors
RF FragmentSeparator
Ge Ge
Ge Ge
RF-kickerNSCL Beta Counting Station(Mantica et al.) With SeGA Ge-detectors
RF FragmentSeparator
Ge Ge-
Ge Ge
+
RF-kickerNSCL Beta Counting Station(Mantica et al.) With SeGA Ge-detectors
RF FragmentSeparator
Ge Ge
Ge Ge
RF-kickerNSCL Beta Counting Station(Mantica et al.) With SeGA Ge-detectors
RF FragmentSeparator
Ge Ge-
Ge Ge
+
RF-kickerNSCL Beta Counting Station(Mantica et al.) With SeGA Ge-detectors
RF FragmentSeparator
Ge Ge
Ge Ge
RF-kickerNSCL Beta Counting Station(Mantica et al.) With SeGA Ge-detectors
RF FragmentSeparator
Ge Ge-
Ge Ge
+
Purification factor = 200
Velocity – dependent selection of fragments
a.u.
)
a.u.
)
Ene
rgy
loss
(a
Ene
rgy
loss
(a
Time of flight (a u ) Time of flight (a u )
al p
ositi
on (m
m)
al p
ositi
on (m
m)
Time of flight (a.u.) Time of flight (a.u.)
Ver
tica
Ver
tica
Ti f fli ht ( )Time of flight (a.u.)
The phase of the RFFS is adjusted to eliminate the most intense contaminants.
Time of flight (a.u.)
Weaker contaminants with a 2π phase difference with respect to the fragments of interest will not be removed.
Pre-FRIB equipmentq p
Adapted from C.K. Gelbke, NSCL Users meeting 2009
FRIB: Facility for Rare Isotope Beams
200 MeV/u, 400 kW d i h isuperconducting heavy-ion
linacFragmentation of fast heavy-ion beams
combined with gas stopping and reacceleration
A potential layout for FRIB tili i tFRIB utilizing current NSCL facilities
MSU and NSCL were chosen as the site for FRIB on 12/11/08. http://www.frib.msu.edu/
• NSCL website: http://www.nscl.msu.edu/p // /
• Nuclear Astro group at NSCL: http://groups nscl msu edu/nero/http://groups.nscl.msu.edu/nero/