ria summer school 2006 exotic beam production and facilities ii brad sherrill, michigan state...

RIA Summer School 2006

Exotic Beam Production and Facilities II

Brad Sherrill, Michigan State University

Lecture I• The Rare Isotope Accelerator Concept• Some history and background• The status of exotic beam plans in the USA

Lecture II• Methods of exotic beam production• Production mechanisms (e.g. fragmentation)• Current world situation for exotic beams

Brad Sherrill, Michigan State University

Lecture I• The Rare Isotope Accelerator Concept• Some history and background• The status of exotic beam plans in the USA

Lecture II• Methods of exotic beam production• Production mechanisms (e.g. fragmentation)• Current world situation for exotic beams


Production Mechanisms

• In-flight Separation

• ISOL – Isotope Separation On-Line

• Neutron induced fission (2-step target)

• In-flight Separation

• ISOL – Isotope Separation On-Line

• Neutron induced fission (2-step target)

Post Acceleration

Driver AcceleratorFragment Separator

beam

Gas cell catcher/ion source

Driver

DriverTarget/Ion Source

Neutrons

Post Acceleration

Post Acceleration

Beams used without stopping


• Good Beam quality ( mm-mr vs. 30 mm-mr transverse)

• Small beam energy spread for fusion studies

• Can use chemistry (or atomic physics) to limit the elements released

• 2-step targets provide a path to MW targets

• High beam intensity leads to 100x gain in secondary ions

• Good Beam quality ( mm-mr vs. 30 mm-mr transverse)

• Small beam energy spread for fusion studies

• Can use chemistry (or atomic physics) to limit the elements released

• 2-step targets provide a path to MW targets

• High beam intensity leads to 100x gain in secondary ions

Advantages/Disadvantages of ISOL/In-Flight

• Provides beams with energy near that of the primary beam

– For experiments that use high energy reaction mechanisms

– Luminosity (intensity x target thickness) gain of 10,000

– Individual ions can be identified

• Efficient, Fast (100 ns), chemically independent separation

• Production target is relatively simple

• Provides beams with energy near that of the primary beam

– For experiments that use high energy reaction mechanisms

– Luminosity (intensity x target thickness) gain of 10,000

– Individual ions can be identified

• Efficient, Fast (100 ns), chemically independent separation

• Production target is relatively simple

In-flight:GSIRIKENNSCLGANIL

ISOL:HRIBFISACSPIRALISOLDE

400kW protons at 1 GeV is 2.4x1015 protons/s


• (p,n) (p,nn) etc. o Ep < 50 MeV

o Used for the production of medical isotopes. o Selective, large production cross sections (100 mb), and

intense (500 A) primary beams.o Used at HRIBF(ISOL), LLN (ISOL), ANL (in-flight) and

Notre Dame (in-flight), Texas A&M (in-flight)

• Fusiono Low energy 5-15 MeV/A and “thin” targetso Selective with fairly large production cross sections.o Used at ANL(in-flight), JYFL (Jyväskylä)

• (p,n) (p,nn) etc. o Ep < 50 MeV

o Used for the production of medical isotopes. o Selective, large production cross sections (100 mb), and

intense (500 A) primary beams.o Used at HRIBF(ISOL), LLN (ISOL), ANL (in-flight) and

Notre Dame (in-flight), Texas A&M (in-flight)

• Fusiono Low energy 5-15 MeV/A and “thin” targetso Selective with fairly large production cross sections.o Used at ANL(in-flight), JYFL (Jyväskylä)

Production Methods – Low Energy


• High, specific production cross sections

• Example: 58Ni(3He,n)60Zn, EHe = 100 MeV

o Production cross section from ALICE: 100 bo 4 g/cm2 targeto Yield of 60Zn is 3x107/pA (LBL 88-inch has 10 pA of

3He)o Heavier beams can have larger cross sections, but require

thinner targets.

• High, specific production cross sections

• Example: 58Ni(3He,n)60Zn, EHe = 100 MeV

o Production cross section from ALICE: 100 bo 4 g/cm2 targeto Yield of 60Zn is 3x107/pA (LBL 88-inch has 10 pA of

3He)o Heavier beams can have larger cross sections, but require

thinner targets.

Example of production by fusion


• Transfer reactionso Significant cross section between 10 - 50 MeV/A (this energy

range implies thin targets, mg/cm2)o High production of nuclei near stability.o Multi-nucleon reactions can be used to produce rare or more

neutron rich nuclei, e.g. GSI mass separator had a program to study neutron rich f-p shell nuclei using neutron transfer.

• Deeply inelastic reactionso Deep inelastic - much of the KE of the beam is deposited in the

target.o Was used to first produce many of the light neutron rich nucleio Is used to study neutron rich nuclei since the products are

“cooler” and fewer neutrons are evaporated than in fusion reactions.

• Transfer reactionso Significant cross section between 10 - 50 MeV/A (this energy

range implies thin targets, mg/cm2)o High production of nuclei near stability.o Multi-nucleon reactions can be used to produce rare or more

neutron rich nuclei, e.g. GSI mass separator had a program to study neutron rich f-p shell nuclei using neutron transfer.

• Deeply inelastic reactionso Deep inelastic - much of the KE of the beam is deposited in the

target.o Was used to first produce many of the light neutron rich nucleio Is used to study neutron rich nuclei since the products are

“cooler” and fewer neutrons are evaporated than in fusion reactions.

Low Energy - Continued


• Fragmentation (NSCL, GSI, RIKEN, GANIL)o Projectile fragmentation of high energy (>50 MeV/A) heavy ionso Target fragmentation of a target with high energy protons or light HIs. In

the heavy ion reaction mechanism community these are called intermediate mass fragments.

• Spallation (ISOLDE, TRIUMF-ISAC)o Name comes from spalling or cracking-off of target pieces.o One of the major ISOLDE mechanisms, e.g. 11Li made from spallation of

Uranium.• Fission (technically not only high energy)

o There is a variety of ways to induce fission (photons, protons, neutrons (thermal, low, high energy)

o The fissioning nuclei can be the target (HRIBF) or the beam (GSI/MSU/RIKEN).

• Coulomb Breakupo At beam velocities of 1 GeV/n the equivalent photon flux as an ion passes

a target is so high the GDR excitation cross section is many barns.

• Fragmentation (NSCL, GSI, RIKEN, GANIL)o Projectile fragmentation of high energy (>50 MeV/A) heavy ionso Target fragmentation of a target with high energy protons or light HIs. In

the heavy ion reaction mechanism community these are called intermediate mass fragments.

• Spallation (ISOLDE, TRIUMF-ISAC)o Name comes from spalling or cracking-off of target pieces.o One of the major ISOLDE mechanisms, e.g. 11Li made from spallation of

Uranium.• Fission (technically not only high energy)

o There is a variety of ways to induce fission (photons, protons, neutrons (thermal, low, high energy)

o The fissioning nuclei can be the target (HRIBF) or the beam (GSI/MSU/RIKEN).

• Coulomb Breakupo At beam velocities of 1 GeV/n the equivalent photon flux as an ion passes

a target is so high the GDR excitation cross section is many barns.

Production Mechanisms – High Energy


Fission Cross Sections

Low energy fission can lead to higher yields for certain nuclides.

This is the basis of the electron driver upgrade of the HRIBF.

Low energy fission can lead to higher yields for certain nuclides.

This is the basis of the electron driver upgrade of the HRIBF.


HRIBF eBeam Upgrade

• Bremsstrahlung from the electron beam induces photo-fission in a uranium carbide target system with a thickness of ~35 g/cm2

• A 50 kW, 100 MeV electron beam incident on such a target would generate a total uranium fission rate 25 times greater than a 20 μA, 50 MeV proton beam.

• In addition, the yield of neutron-rich species is shifted much farther from stability than for proton induced fission.

• This would result in a factor of 1,000 to 10,000 increase in beam intensities at HRIBF

• Bremsstrahlung from the electron beam induces photo-fission in a uranium carbide target system with a thickness of ~35 g/cm2

• A 50 kW, 100 MeV electron beam incident on such a target would generate a total uranium fission rate 25 times greater than a 20 μA, 50 MeV proton beam.

• In addition, the yield of neutron-rich species is shifted much farther from stability than for proton induced fission.

• This would result in a factor of 1,000 to 10,000 increase in beam intensities at HRIBF

http://www.phy.ornl.gov/hribf/initiatives/electrons/


Projectile Fragment

SpallationProduct

Intermediate Mass Fragment/ Target Fragment

Terminology for High Energy Reactions

The fragment could emit nucleons (fragmentation) and/or fission

The fragment could emit nucleons (fragmentation) and/or fission

See the lectures of D BazinSee the lectures of D Bazin

ABRABLA - A. R. Junghans, K.-H. Schmidt et al, Nucl. Phys. A 629 (1998) 635ABRABLA - A. R. Junghans, K.-H. Schmidt et al, Nucl. Phys. A 629 (1998) 635


Overview of the In-Flight Technique

Wedge location

D = 5 cm/%

R = 2500 p/p

100 pnA 86Kr

5 kW Beam power

8 msr

p = 5%

Example: The NSCL Coupled Cyclotron FacilityExample: The NSCL Coupled Cyclotron Facility

65% of the 78Ni is transmitted

Morrissey and Sherrill: Euroschool LecturesMorrissey and Sherrill: Euroschool Lectures


Multiple stages of separation

Z

N

P re-S eparator M ain-S eparator

S n132S n132S n132

H. Geissel et al. NIM B

Higher energy provides cleaner separation.

Higher energy provides cleaner separation.


LISE++ Simulation Code

The code operates under Windows and provides a highly user-friendly interface. It can be downloaded freely from the following internet address: http://www.nscl.msu.edu/lise

O. Tarasov et al.


0

1

2

3

4

5

0 5 10 15 20 25

Momentum Acceptance [%]

Yie

ld [

pps/

pA

] 100 MeV/u

200 MeV/u

400 MeV/u

600 MeV/u

1000 MeV/u

0

1

2

3

4

5

0 5 10 15 20 25

Momentum Acceptance [%]

Yie

ld [

pps/

pA

] 100 MeV/u

200 MeV/u

400 MeV/u

600 MeV/u

1000 MeV/u

Facility Specifications

78Ni from 86Kr

No secondary reactions

Tony Nettleton


b/m

rad

-40-20

-60

0204060

a/mrad-50 0 50

dp/p in %-10 0 10

800

1200

400

0

1600

b/m

rad

-40-20

-60

0204060

a/mrad-50 0 50

dp/p in %-10 0 10

800

1200

400

0

1600

b/m

rad

-40-20

-60

0204060

a/mrad-50 0 50 -10 0 10

dp/p in %

400

300

200

100

0

500

b/m

rad

-40-20

-60

0204060

a/mrad-50 0 50 -10 0 10

dp/p in %

400

300

200

100

0

500

Fragmentation at 400MeV/u

• Angles ≤ ± 20 mrad

• Momentum ± 3 - 8 %

Relatively ‘easy’ due to small phase space

Momentum distrib.

100Sn

200W

M. Hausmann, T. Nettleton


b/m

rad

-40-20

-60

0204060

a/mrad-50 0 50 -10 0 10

dp/p in %

600500400300200100

0

b/m

rad

-40-20

-60

0204060

a/mrad-50 0 50 -10 0 10

dp/p in %

600500400300200100

0

b/m

rad

-40-20

-60

0204060

a/mrad-50 0 50 -10 0 10

dp/p in %

0

100

200

300

400

b/m

rad

-40-20

-60

0204060

a/mrad-50 0 50 -10 0 10

dp/p in %

0

100

200

300

400

In-Flight Fission at 400 MeV/u

•Angles ± 40 - 60 mrad

• Rigidity ± 6 - 10 %

• Plus correlations due to fission kinematics

More challenging due to larger phase space

132Sn

76Ni

M. Hausmann, T. Nettleton


NSCL Coupled Cyclotron Project

Experimental Areas

Cyclotrons – up to MeV/uCyclotrons – up to MeV/u

ECR

Operational – will study N=82 nuclei and nuclei along the neutron drip line up to mass 30.

Operational – will study N=82 nuclei and nuclei along the neutron drip line up to mass 30.


Particle Identification


Beams Produced with CCF/A1900


GSI Current RNB Facility

• Production of 100Sn and 78Ni

• Hundreds of new masses and isotopes, …


Cold Fragmentation Studied at GSI

197Au + Be at 950 A MeV

J. Benlliure, K.-H. Schmidt, et al. Nuclear Physics A 660 (1999) 87

5


The GSI FAIR Facility Layout

from J. Nolen ANL


RIKEN Radioactive Ion Beam Factory

from J. Nolen ANL


RIKEN RIBF Heavy-ion accelerator system

An ion source current of 32 p-μamps is required to reach uranium beam goal. An ion source current of 32 p-μamps is required to reach uranium beam goal.


Targets and Production Mechanisms

from J. Nolen ANL


I = Ib Tuseable diff des eff is_eff accel_effI = Ib Tuseable diff des eff is_eff accel_eff

H. Ravn

- production cross section

· Ib - beam intensity

· Tuseable - usable target

thickness diff – diffusion efficiency des – desorption efficiency eff – effusion efficiency is_eff - ionization efficiency accel_eff - acceleration

efficiency

- production cross section

· Ib - beam intensity

· Tuseable - usable target

thickness diff – diffusion efficiency des – desorption efficiency eff – effusion efficiency is_eff - ionization efficiency accel_eff - acceleration

efficiency

Production is only one part of the equation

target


ISOLDE

http://isolde.web.cern.ch/ISOLDE/

CERN

PSB

1 GeV protons

2 mA

Intensities up to 1011 pps

CERN

PSB

1 GeV protons

2 mA

Intensities up to 1011 pps

Accelerate to 3.0 MeV/u


SPIRAL at GANIL

http://www.ganil.fr/spiral/index.html


GANIL SPIRAL-2

Completion

~2011

Completion

~2011


ISAC Radioactive Beam Facility - ISOL

Beams are produced by 500 MeV protons from TRIUMF cyclotron.Beams are produced by 500 MeV protons from TRIUMF cyclotron.

2x109 22Na/s

ISAC-II underway

ISAC-II underway


ISAC-2 overview

ISAC has a fixed 500-MeV proton beam driver with 50-kW power.

ISAC has a fixed 500-MeV proton beam driver with 50-kW power.


Texas A&M Upgrade Project

http://cyclotron.tamu.edu/• Radioactive beams to 50 MeV/u• Difficult isotopes from the ion-guide

• Radioactive beams to 50 MeV/u• Difficult isotopes from the ion-guide


EURISOL

5 MW Proton LINAC

http://www.ganil.fr/eurisol/index.html


Overview of the RIA Concept


A combination of forces working together is required to obtain

•Fast extraction times over the full volume

•High efficiency over the full volume

•Tolerance to high intensity

A combination of forces working together is required to obtain

•Fast extraction times over the full volume

•High efficiency over the full volume

•Tolerance to high intensity

Forces in gas catcher system

from J. Nolen ANL


Momentum Compensation

Diagram: H. Weick et al., NIM B 164-165 (2000) 168

FWHM = 32 atm-m 4He

FWHM = 0.93 atm-m 4He

Above: Range compression of 350 Mev/u 130Cd produced from 500 MeV/u 136Xe(MOCADI simulation)

130Cd

0

0.5

1

1.5

2

0 500 1000 1500 2000 2500

0

0.5

1

1.5

2

0 500 1000 1500 2000 2500

Ran

ge F

WH

M (

atm

-m)

Resolving Power

350 MeV/u 130Cd range width

M. Amthor


beam from A1900

9.4 T Penningtrap system

mass measurements

Many systematic studies:

L. Weissman et al., NIM A522 (2004) 212, NIM A531 (2004)

416, Nucl. Phys. A746 (2004) 655c, NIM A540 (2005) 245.

P/P 0.5 %, gas_cell_1.2_50

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

0.040

0.045

1650 1670 1690 1710 1730 1750 1770 1790

18 k pps

6 k pps

2 k pps

0.4 k pps

0.04 k pps

gas-equivalent

stopping /10

-10 -5 0 5 10

18

19

20

21

22

23

24

TO

F [

s]

fRF

[Hz] - 7595522

38Ca++

T1/2 = 440 ms

R = 2106

m/m < 10-8

First nuclear physics experiment with thermalized beams from fast beam fragmentation

LEBIT project

92 MeV/U 38Ca/37K

Degrader thickness m

effi

ciency

Gas Stopping in use at the NSCL


<Normalized background substracted Si counts>

0

0.001

0.002

0.003

0.004

0.005

0.006

0.007

2150 2200 2250 2300 2350 2400 2450 2500 2550

Degrader Thickness [mg/cm2]

<Si /

Sci

41 -

bck

g>

17. Feb 05

0

5

10

15

20

1900 2000 2100 2200 2300 2400 2500

degrader thickness [mg/cm^2]

co

un

ts O

TO

F /

MU

SIC

GSI experiment S258

Savard(ANL), Scheidenberger (GSI) et al.

GSI experiment S258

Savard(ANL), Scheidenberger (GSI) et al.

Bragg peak from 56Ni beamBragg peak from 54Co beamBragg peak from 52Fe beam

54Co52Fe

~ 50 % of radioactive ions stopped in the gas catcher were extracted as

a radioactive ion beam!

ANL, GSI, KUL, MSU, RIKEN, …

RIA prototype gas catcher tested at GSI


ANL Upgrade based on 252Cf Fission

Guy Savard, ANL


ANL ATLAS upgrade: CARIBU


Yields from the ANL Upgrade

Guy Savard, ANL


SRIM & PIC calculation by M.Facina

0 100 200 300 400 500

60

80

100

120

140

160

radi

al d

ime

nsi

on

(mm

)

axial dimension (mm)

He+

Stopping volume Stopping volume 75 cm 75 cm33

Ionization Ionization 1.7 x 10 1.7 x 1066 IP/ionIP/ion

Extraction of He+

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

0 100 200 300 400 500 600 700

time (ms)

effi

cien

cy

1e0/s

1e1/s

1e2/s

1e3/s

1e4/s

1e5/s

1e6/s

~0.53%

~2.15 %

~4.55%

~8.80%

~14.5%

~0.054%

HeHe+ + created by a 100 pps created by a 100 pps 3838Ca beam in 760 TorrCa beam in 760 Torr


Cyclotron Gas Stopper Concept

RFQ Ion Guide

RF Carpet

Charge Collection Electrodes

Test (Fission) Source

2Tesla Magnet

Pumping

10 mbar He

Entrance window/degrader

extracted beam

injectedbeam

Gas-filled weakly-focusing cyclotron magnet w/ RF guiding techniques at end-of-range

Low gas pressure

long stopping path

fast drift & extraction

Separate He+ from rare ions

minimal space-charge

Exotic atom studies in a cyclotron trap for antiprotons, pions, and muons

L.M. Simons, Hyperfine Interactions 81 (1993) 253

Proposal for a cyclotron ion guide with RF carpet

I. Katayama, M. Wada, Hyperfine Interactions 115 (1998) 165

A Study of Gas-Stopping of Intense Energetic Rare Isotope Beams

G. Bollen, D.J. Morrissey, S. Schwarz, NIM A550 (2005) 27

Features/Expectations:


Initial Stopping Calculations

degrader

100 MeV/A Br [ 2.6 mm Al ] 610 MeV Br

Field Bmax = 2 T, n = 0.2

10 mbar He

Beam simulations of ions in gas-filled weak-focusing magnet by Bollen

Beam simulations of ions in gas-filled weak-focusing magnet by Bollen

High space-charge and stopped-ion regions are separated ! Intensity limits > 108/s

High space-charge and stopped-ion regions are separated ! Intensity limits > 108/s

Energy loss or Ionization density

Energy loss or Ionization density

Stopped-ion distribution lies inside dashed circle

Top view


NSCL Stopping Cyclotron (Under Design)

Superconducting magnet system Bmax = 2 T, n = 0.2, rinj = 0.7 m

High EnergyBeam

D.Lawton, A.Zeller (NSCL)


Beam Simulation including Injection

One Trajectory in ‘real’ field

Energy vs. Position

degrader

100 MeV/A 79Br on 2.6mm Al 610 MeV 78Br

F. Marti (NSCL)


Minimizing extraction time

Simulations of ion motion on RF carpets in 2 Tesla field

Low gas pressure (10 mbar compared to 200 - 1000 mbar in present systems) Time for collection onto carpet and transport out of gas stopper < 5 ms !

Low gas pressure (10 mbar compared to 200 - 1000 mbar in present systems) Time for collection onto carpet and transport out of gas stopper < 5 ms !

RF 400V; 1.5MHzDC gradient 20V/cmSpacing 1 mm, 0.5 mm thick

RFQ Ion Guide

RF Carpet

Charge Collection Electrodes

Test (Fission) Source

2Tesla Magnet

Pumping

10 mbar He

Entrance window/degrader

extracted beam

injectedbeam


NSCL Reacceleration Stage Options

Reaccelerated beam area

Reaccelerated beam area

Stage I: 3 MeV/uStage I: 3 MeV/u

Stage II: 12 MeV/uStage II: 12 MeV/u


You ask: Should I switch fields?

• Construction of a 1 B$ facility in the US in the next 5 years is unlikely

• There are positive signs (3rd on the DOE list of facility priorities; congressional mandate of RIA; highest NSAC priority) that something on the scale of 600 M$ will happen

• This is a very active field world-wide

• NSCL, TRIUMF, HRIBF, ANL, T A&M, etc.

• Upgrades at NSCL, ANL, HRIBF

• Large scale international facilities: FAIR, RIBF, SPRIRAL II, EURISOL, …

• There are exciting, important questions to answer

• Construction of a 1 B$ facility in the US in the next 5 years is unlikely

• There are positive signs (3rd on the DOE list of facility priorities; congressional mandate of RIA; highest NSAC priority) that something on the scale of 600 M$ will happen

• This is a very active field world-wide

• NSCL, TRIUMF, HRIBF, ANL, T A&M, etc.

• Upgrades at NSCL, ANL, HRIBF

• Large scale international facilities: FAIR, RIBF, SPRIRAL II, EURISOL, …

• There are exciting, important questions to answer


Additional Material


RIA White Papers

One of the best places to find out more information regarding RIA is the RIA users web site.

Overall info:

http://www.orau.org/ria/

White papers:

http://www.orau.org/ria/pubs.htm

One of the best places to find out more information regarding RIA is the RIA users web site.

Overall info:

http://www.orau.org/ria/

White papers:

http://www.orau.org/ria/pubs.htm


Universality of Production Cross Sections

Na isotopesNa isotopes


The production yield of residues saturates with a total beam energy of a few GeV. Limiting Fragmentaton

H. Ravn - “The saturation cross-section for more exotic species may well first be reached beyond 5 GeV.”

Kaufman and Steinberg, PRC 22 (80) 167.

Limiting Fragmentation


Moretto and Wozniak, Ann. Rev. 45 (93)

Moretto and Wozniak, Ann. Rev. 45 (93)

p + Xeat 48.5 degrees

Limiting Fragmentation continues to high energy

ria summer school 2006 exotic beam production and facilities ii brad sherrill, michigan state...

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