HRIBF HRIBF - proton-rich beams Dan Stracener HRIBF Users Workshop November 13, 2009

HRIBFHRIBF

HRIBF - proton-rich beams

Dan Stracener

HRIBF Users Workshop

November 13, 2009

2 Managed by UT-Battellefor the U.S. Department of Energy

Outline

• Status of proton-rich beams at HRIBF– Accelerated beam intensities

– Targets currently used (what are the limitations?)

• Enhancements to the quality of p-rich beams at HRIBF– Availability of HPTL/IRIS2 for high-power target development

– Larger targets and beam rastering at HPTL/IRIS2

– Effects of the C70 upgrade on the p-rich beams• Higher proton energy and intensity• Higher beam intensities for deuterons and alphas• Increased reliability (allows for more high-power target development)• New beam production capabilities


Proton-rich Radioactive Ion Beams

• Seven different targets used• Three different ion sources• 33 radioactive beams

2m

HfO2 for 17,18F beams

CeS on RVC matrix for 34Cl


Accelerated Proton-rich Radioactive Ion Beams

RIB Energy Range Highest Intensity ORIC Current Purity

(MeV) (pps on target) (A on target) (%)

7Be 4 – 27 4.0 x 106 n/a 10010Be 29 – 107 2.7 x 107 n/a > 9917F 10 – 170 1.0 x 107 5 10018F 10 – 108 6.0 x 105 1.5 10026gAl 13 – 117 1.6 x 107 n/a 10067Ga 160 2.5 x 105 3 > 90

69As 160 2.0 x 106 3 ~ 1070As* 140 2.0 x 103 0.01 < 10-6

* This beam was used for commissioning of the RIB Injector


Additional Proton-rich Radioactive Ion Beams(yields measured at OLTF or HPTL)

RIB Target Estimates from yield measurements

Intensity (pps) ORIC Current (A) Purity (%)

25Al SiC, Nb5Si31 x 104 7 > 99

26mAl SiC, Nb5Si31 x 104 5 > 99

26Si Al2O31 x 103 1 > 99

27Si Al2O31 x 103 1 > 99 (SiS+)

34Cl CeS 5 x 103 7 ?60Cu liq. Ni 3 x 103 3 ?

72Se liq. Ge 1 x 106 1 ?56Co nickel 4 x 108 15 9556Ni nickel 2 x 107 15 > 99


Experiments Completed During Recent RIB Campaign(Multi-sample Cs-sputter ion source)

Dates Experiment Beam BOT Intensity

# of hours

3/4 - 3/12 RIB-186 (Bardayan) 26gAl 1.5 x 106 175

3/21 – 3/22 RIB-157 (Greife) 7Be 8 x 105 36

3/23 – 3/31 RIB-153 (Pain) 26gAl 1.6 x 107 174

4/3 – 4/9 RIB-170 (Jones) 10Be 1 x 107 155

4/20 – 4/23 RIB-161 (Freer) 10Be 2.7 x 107 88

4/24 RIB-161 (Freer) 7Be 7 x 104 22

4/27 – 5/1 RIB-157 (Greife) 7Be 2 x 105 86

5 experiments – 736 hours of radioactive beam on target5 experiments – 736 hours of radioactive beam on target

OAK RIDGE NATIONAL LABORATORY

U.S. DEPARTMENT OF ENERGY

HfO2 fibers (production of 17F and 18F) Uranium carbide (production of n-rich beams via proton-induced

fission) Molten metals

germanium for production of As, Ga, and Se isotopes nickel for production of Cu isotopes

Ni pellets (56Ni via (p,p2n) reaction – 56Co contamination) Cerium sulfide (production of 33Cl and 34Cl)

thin layers deposited on W-coated carbon matrix Silicon carbide (production of 25Al and 26Al)

fibers (15 m), powder (1 m), thin layers on carbon matrix, solid discs also developing metal silicides (e.g. Nb5Si3 disks)

Aluminum oxide (production of 26Si and 27Si) thin fibers (6m) with sulfur added for transport

7Be, 10Be, 26gAl sputter targets mixed with copper, silver, or niobium powders

RIB Production Targets


2m

HfO2 Target for 17,18F Beam Production

FndO 1716 ),( FpnO 1816 ),(&


25Al and 26mAl (SiC target at the OLTF)

15 m diameter SiC fibers 1 m diameter SiC powder SiC does not sinter Maximum operating temperature is 1650 C 25Al yields were about the same in both targets Increase yield significantly (x10) by adding fluorine

to system and extract as AlF+

AlpSi 2528 ),( AlndSi 2528 ),(

AlpnpSi 2628 )2,(

AldSi 2628 ),(



Performed tests of SiC fiber target with 54 MeV proton beams up to 9 A (just over 4 days of irradiation)

25Al and 26mAl yields up to 106 pps as AlF+

Almost equal amounts of Al+ and AlF+ Also observed Mg+ and Na+ beams

but not as fluoride molecular ions Observed 17F from (p,3) !

SiC Target Tests at the HPTL


100

1000

10000

100000

24 25 26 27 28 29 30

Mass (amu)

2 microA

5 microA

10 microA

12 microA

SiC Target Tests at the HPTL• We have conducted on-line tests at the HPTL with SiC disks using a

target design that allows for increased radiative cooling

• This work is a collaboration with a group from Legnaro (SPES Project)

• Normalized yields are less than from the SiC fiber targets but the production beam current limit is somewhat higher so the extracted beam intensities are comparable

February, 2007 data


Nb5Si3 targets

• Yields of 25Al and 26mAl measured at the HPTL with proton beams up to 7 A

• Motivation: lack of carbon atoms in the system will reduce the chance of forming the AlC molecule, which is quite refractory

• Normalized yields were lower than measured with SiC fiber targets, possibly due to high density (and low porosity) of these targets



Thin layer of CeS (5 m thick) deposited onto a tungsten-coated carbon matrix same matrix that is used for UC targets

Maximum operating temp. is 1900 C Used to produce 33Cl and 34Cl beams

32S(d,n)33Cl (T1/2 = 2.5 sec) 34S(p,n)34Cl & 34S(d,2n)34Cl (T1/2 = 32.2 min)

Initial on-line tests measured up to 106 ions/sec/A of 34Cl+

no 33Cl observed extracted from ion source as AlCl+ very little Al vapor was present in the target natS used to make target (natural abundance of 34S is 4.2%)

Targets showed no change during on-line test Ce2S3 cannot be used since it converts to CeS at < 1600 C and

has a high vapor pressure of sulfur

34Cl (CeS target at the OLTF)


34Cl Yields vs target temperature

0.0E+00

2.0E+05

4.0E+05

6.0E+05

8.0E+05

1.0E+06

1.2E+06

1.4E+06

1.6E+06

1780 1800 1820 1840 1860 1880 1900 1920 1940 1960

Target temperature (C)

Yie

lds

(io

ns/

s/ A

)

34Cl

34ClAl


Al2O3 target for production of 26Si and 27Si beams

SinpAl 2727 ),(

SinpAl 2627 )2,(

target holder (1.5 cm dia. x 7.6 cm)

target before test

target after test

Max. operating temp. is 1900 C Tested at 1750 C Measured yield of 27Si is 2000 ions/sec/A Observed as molecular ion (SiS+)


New RIBs delivered to experiments (2009)

• Beams of 10Be (T½ = 1.5 x 106 years) and 26gAl (T½ = 7.1 x 105 years) have been accelerated in the Tandem and delivered to experiments

• Used a Cs-sputter ion source on IRIS1 to produce negative ions

• The cathodes were produced from liquid samples using a technique similar to one used for producing cathodes of 7Be (2003 and 2005)

– 3 x1019 atoms (540 g or 8 Ci) of 10Be in about 20 ml of 1.5M HCl

– 2 x 1017 atoms (6.6 g or 0.2 Ci) of 26gAl

10Be 26gAl


10Be and 26gAl cathodes for Cs-sputter ion source

• Made three 10Be cathodes (used about 10% of sample)

– Two cathodes with about 2 x 1017 atoms (one has not been used)

– One cathode with about 2 x 1018 atoms

• Made two 26gAl cathodes (used about 15% of sample)

– Each cathode contained about 1.2 x 1016 atoms

• Also produced two cathodes containing 7Be atoms from a 3 GBq sample purchased from Atomki in Hungary

– Cathodes had 9 x 1015 and 1 x 1015 atoms of 7Be


Liquid Ge targets for As and Se beams

Purchased enriched 70Ge from Russia for production of 69,70As and 72Se

70Ge(p,2n)69As70Ge(,2n)72Se

Germanium chips are melted (about 1200 C) to form a pellet and inserted into a graphite target holder


Path to improving the p-rich beams

• High-power target development– Use the availability and capabilities of the HPTL/IRIS2 to facilitate development

of ISOL production targets that can withstand higher production beam currents

– Develop larger targets maintain high target temperatures without large thermal gradients

– Raster the production across the face of the larger target to increase the production rates without increasing the power density in the target material

• Improve the production beam characteristics– Higher proton beam energy from the C70 would increase the production rate in

some select cases

– Higher production beam currents from the C70 will be used to take advantage of the high-power targets that are developed

– Increased driver accelerator reliability will result in not only more beam time available for RIB experiments but also more time available for high-power target development


A Possible Thin Target Geometry

Actual geometry used for liquid Ge target for As beams(1.2 cm dia. x 0.6 cm thick)

Target thickness is 0.08 cm



Potential Target Holder and Heater Design

RIB

Production Target

Target heater

ORIC

14” TIS enclosure

200

800

1400

2000

2600

3200

0.0 0.5 1.0 1.5 2.0 2.5 3.0t (s)

T (

K)

Limiting temperature

Maximum irradiation time

The UC/RVC target could not withstand direct irradiationwith 42 MeV, 100 A proton beams for longer than 2 seconds

Target irradiated with high power beamsTarget irradiated with high power beams



Beam Rastering Capabilities

Demonstrated ability to raster a 1-cm diameter beam over a 5-cm diameter target (2 dimensions) with existing steerers (Tony Mendez)

Made simulations to determine the required raster rate and amplitude (Yan Zhang)

Larger entrance port (4” dia.) into TIS enclosure at HPTL/IRIS2 allows for rastered production beams

Especially important for the p-rich beams where the production targets are often less refractory than UC HfO2 limited to 3 A of deuterons (Al2O3 limit is < 1 A) Limits for other production targets for p-rich beams need to be

experimentally determined


Temperature variations due to beam scanning

2350

2400

2450

2500

2550

0.0 0.2 0.4 0.6 0.8 1.0t (s)

T (

K)

x = 0

x = 1 cm

x = 2 cm

UC2/RVC target (1.2 g/cc), proton beam 50 MeV, 20 A

Beam scan frequency: 1.67 Hz ( f > 8 Hz for T < 20 K)


proton-rich RIB Production at Low E• Fusion-evaporation reactions produce large cross sections

localized in beam energy

0

20

40

60

80

100

120

140

160

0 10 20 30 40 50 60

70Ge(p,xn)

67Ga66Ga65Ga

(E

) (

mb)

Ep (MeV)

0

100

200

300

400

500

600

700

0 10 20 30 40 50 60

70Ge(p,xn)

70As69As68As

(E

) (

mb)

Ep

(MeV)


Estimates of p-rich beam intensities with upgrades

RIB Target Prod. Beam Limit Accelerated Beam Intensity (pps on target)

(A) HRIBF now With improved target design

with C70 and improved targets

7Be Li 1H 30 2 x 107

10Be n/a n/a 3 x 107

17F HfO22H 5 2 x 107 4 x 107 2 x 108

18F HfO24He 1.5 2 x 106 4 x 106 2 x 107

25Al SiC, Nb5Si31H 7 1 x 104 2 x 104 1 x 105

26mAl SiC, Nb5Si32H 5 1 x 104 2 x 104 1 x 105

26gAl n/a n/a 2 x 107

26Si Al2O31H <1 1 x 103 1 x 104 2 x 104

27Si Al2O31H <1 1 x 103 1 x 104 1 x 104

34Cl CeS 1H 7 5 x 103 1 x 104 5 x 104

60Cu liquid Ni 1H 3 3 x 103 1.5 x 104 3 x 104

61Cu liquid Ni 1H 3 1 x 103 5 x 103 1 x 104

62Cu liquid Ni 1H 3 1 x 103 5 x 103 1 x 104






65Ga liquid Ge 1H 3 1 x 103 5 x 103 2 x 104

66Ga liquid Ge 1H 3 1 x 104 5 x 104 2 x 105

67Ga liquid Ge 1H 3 3 x 105 1.5 x 106 6 x 106

68Ga liquid Ge 1H 3 1 x 105 5 x 105 1 x 106

70Ga liquid Ge 1H 3 1 x 104 5 x 104 1 x 105

69As liquid Ge 1H 3 2 x 106 1 x 107 2 x 107

70As liquid Ge 1H 3 1 x 107 5 x 107 1 x 108

71As liquid Ge 1H 3 1 x 106 5 x 106 1 x 107

72As liquid Ge 1H 3 1 x 107 5 x 107 1 x 108

73As liquid Ge 1H 3 1 x 107 5 x 107 1 x 108

74As liquid Ge 1H 3 1 x 107 5 x 107 1 x 108

76As liquid Ge 1H 3 1 x 106 5 x 106 1 x 107

77As liquid Ge 1H 3 1 x 105 5 x 105 1 x 106






70Se liquid Ge 4He 1 1 x 104 5 x 104 5 x 104





11C graphite 1H 15 8 x 104 8 x 104 8 x 105

56Co solid Ni 1H 15 4 x 108 4 x 108 4 x 109

56Ni solid Ni 1H 15 2 x 107 2 x 107 2 x 108


New Proton-rich Radioactive Beams(possible with increased energy, intensity, and reliability)

• 14,15O from SiC or graphite targets – (,xn) reactions

• 21Na from SiC targets using (p,2) reaction

• 29,30P from Al2O3, SiC, or CeS targets

• 30,31S from SiC targets using 4He production beams

• 33Cl from CeS targets using 1H or 2H production beams

• 67,68As from liquid Ge target – (p,3n) or (p,4n) reactions

• Long-lived isotopes (many possibilities)– Irradiate samples using the secondary proton beam

– 68Ge (could be produced by irradiating a water-cooled Ga target with a proton beam from the C70 and inserting the sample into a Cs-sputter ion source)

Documents

HRIBF HRIBF - proton-rich beams Dan Stracener HRIBF Users Workshop November 13, 2009