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/