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

2Managed by UT-Battelle for 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

3Managed by UT-Battelle for the U.S. Department of Energy Proton-rich Radioactive Ion Beams Seven different targets used Three different ion sources 33 radioactive beams 2m2m HfO 2 for 17,18 F beams CeS on RVC matrix for 34 Cl

4Managed by UT-Battelle for the U.S. Department of Energy Accelerated Proton-rich Radioactive Ion Beams RIBEnergy RangeHighest IntensityORIC CurrentPurity (MeV)(pps on target) (  A on target) (%) 7 Be 4 – x 10 6 n/a Be 29 – x 10 7 n/a> F 10 – x F 10 – x g Al 13 – x 10 7 n/a Ga x > As x ~ As* x < * This beam was used for commissioning of the RIB Injector

5Managed by UT-Battelle for the U.S. Department of Energy Additional Proton-rich Radioactive Ion Beams (yields measured at OLTF or HPTL) RIBTargetEstimates from yield measurements Intensity (pps) ORIC Current (  A) Purity (%) 25 AlSiC, Nb 5 Si 3 1 x > 99 26m AlSiC, Nb 5 Si 3 1 x > SiAl 2 O 3 1 x > SiAl 2 O 3 1 x > 99 (SiS + ) 34 ClCeS5 x ? 60 Culiq. Ni3 x ? 72 Seliq. Ge1 x ? 56 Conickel4 x Ninickel2 x > 99

6Managed by UT-Battelle for the U.S. Department of Energy Experiments Completed During Recent RIB Campaign (Multi-sample Cs-sputter ion source) DatesExperimentBeamBOT Intensity # of hours 3/4 - 3/12RIB-186 (Bardayan) 26g Al1.5 x /21 – 3/22RIB-157 (Greife) 7 Be8 x /23 – 3/31RIB-153 (Pain) 26g Al1.6 x /3 – 4/9RIB-170 (Jones) 10 Be1 x /20 – 4/23RIB-161 (Freer) 10 Be2.7 x /24RIB-161 (Freer) 7 Be7 x /27 – 5/1RIB-157 (Greife) 7 Be2 x experiments – 736 hours of radioactive beam on target

O AK RIDGE NATIONAL L ABORATORY U.S. D EPARTMENT OF E NERGY  HfO 2 fibers (production of 17 F and 18 F)  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 ( 56 Ni via (p,p2n) reaction – 56 Co contamination)  Cerium sulfide (production of 33 Cl and 34 Cl)  thin layers deposited on W-coated carbon matrix  Silicon carbide (production of 25 Al and 26 Al)  fibers (15  m), powder (1  m), thin layers on carbon matrix, solid discs  also developing metal silicides (e.g. Nb 5 Si 3 disks)  Aluminum oxide (production of 26 Si and 27 Si)  thin fibers (6  m) with sulfur added for transport  7 Be, 10 Be, 26g Al sputter targets  mixed with copper, silver, or niobium powders RIB Production Targets

8Managed by UT-Battelle for the U.S. Department of Energy 2m2m HfO 2 Target for 17,18 F Beam Production &

9Managed by UT-Battelle for the U.S. Department of Energy 25 Al and 26m Al (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  25 Al yields were about the same in both targets  Increase yield significantly (x10) by adding fluorine to system and extract as AlF +

O AK R IDGE N ATIONAL L ABORATORY U.S. D EPARTMENT OF E NERGY  Performed tests of SiC fiber target with 54 MeV proton beams up to 9  A (just over 4 days of irradiation)  25 Al and 26m Al yields up to 10 6 pps as AlF +  Almost equal amounts of Al + and AlF +  Also observed Mg + and Na + beams but not as fluoride molecular ions  Observed 17 F from (p,3  ) ! SiC Target Tests at the HPTL

11Managed by UT-Battelle for the U.S. Department of Energy 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

12Managed by UT-Battelle for the U.S. Department of Energy Nb 5 Si 3 targets Yields of 25 Al and 26m Al 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

O AK R IDGE N ATIONAL L ABORATORY U.S. D EPARTMENT OF E NERGY  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 33 Cl and 34 Cl beams  32 S(d,n) 33 Cl (T 1/2 = 2.5 sec)  34 S(p,n) 34 Cl & 34 S(d,2n) 34 Cl (T 1/2 = 32.2 min)  Initial on-line tests  measured up to 10 6 ions/sec/  A of 34 Cl +  no 33 Cl observed  extracted from ion source as AlCl +  very little Al vapor was present in the target  nat S used to make target (natural abundance of 34 S is 4.2%)  Targets showed no change during on-line test  Ce 2 S 3 cannot be used since it converts to CeS at < 1600 C and has a high vapor pressure of sulfur 34 Cl (CeS target at the OLTF)

14Managed by UT-Battelle for the U.S. Department of Energy

15Managed by UT-Battelle for the U.S. Department of Energy Al 2 O 3 target for production of 26 Si and 27 Si beams 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 27 Si is 2000 ions/sec/  A  Observed as molecular ion (SiS + )

16Managed by UT-Battelle for the U.S. Department of Energy New RIBs delivered to experiments (2009) Beams of 10 Be (T ½ = 1.5 x 10 6 years) and 26g Al (T ½ = 7.1 x 10 5 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 7 Be (2003 and 2005) – 3 x10 19 atoms (540  g or 8  Ci) of 10 Be in about 20 ml of 1.5M HCl – 2 x atoms (6.6  g or 0.2  Ci) of 26g Al 10 Be 26g Al

17Managed by UT-Battelle for the U.S. Department of Energy 10 Be and 26g Al cathodes for Cs-sputter ion source Made three 10 Be cathodes (used about 10% of sample) – Two cathodes with about 2 x atoms (one has not been used) – One cathode with about 2 x atoms Made two 26g Al cathodes (used about 15% of sample) – Each cathode contained about 1.2 x atoms Also produced two cathodes containing 7 Be atoms from a 3 GBq sample purchased from Atomki in Hungary – Cathodes had 9 x and 1 x atoms of 7 Be

18Managed by UT-Battelle for the U.S. Department of Energy Liquid Ge targets for As and Se beams Purchased enriched 70 Ge from Russia for production of 69,70 As and 72 Se 70 Ge(p,2n) 69 As 70 Ge( ,2n) 72 Se Germanium chips are melted (about 1200 C) to form a pellet and inserted into a graphite target holder

19Managed by UT-Battelle for the U.S. Department of Energy 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

20Managed by UT-Battelle for the U.S. Department of Energy 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

O AK RIDGE NATIONAL L ABORATORY U.S. D EPARTMENT OF E NERGY Potential Target Holder and Heater Design RIB Production Target Target heater ORIC 14” TIS enclosure

The UC/RVC target could not withstand direct irradiation with 42 MeV, 100  A proton beams for longer than 2 seconds Target irradiated with high power beams

O AK RIDGE NATIONAL L ABORATORY U.S. D EPARTMENT OF E NERGY 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  HfO 2 limited to 3  A of deuterons (Al 2 O 3 limit is < 1  A)  Limits for other production targets for p-rich beams need to be experimentally determined

24Managed by UT-Battelle for the U.S. Department of Energy Temperature variations due to beam scanning UC 2 /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)

25Managed by UT-Battelle for the U.S. Department of Energy proton-rich RIB Production at Low E Fusion-evaporation reactions produce large cross sections localized in beam energy

26Managed by UT-Battelle for the U.S. Department of Energy Estimates of p-rich beam intensities with upgrades RIBTargetProd. BeamLimitAccelerated Beam Intensity (pps on target) (  A) HRIBF nowWith improved target design with C70 and improved targets 7 BeLi 1H1H302 x Ben/a 3 x FHfO 2 2H2H52 x x x FHfO 2 4 He1.52 x x x AlSiC, Nb 5 Si 3 1H1H71 x x x m AlSiC, Nb 5 Si 3 2H2H51 x x x g Aln/a 2 x SiAl 2 O 3 1H1H<11 x x x SiAl 2 O 3 1H1H<11 x x ClCeS 1H1H75 x x x Culiquid Ni 1H1H33 x x x Culiquid Ni 1H1H31 x x x Culiquid Ni 1H1H31 x x x 10 4

27Managed by UT-Battelle for the U.S. Department of Energy Estimates of p-rich beam intensities with upgrades RIBTargetProd. BeamLimitAccelerated Beam Intensity (pps on target) (  A) HRIBF nowWith improved target design with C70 and improved targets 65 Galiquid Ge 1H1H31 x x x Galiquid Ge 1H1H31 x x x Galiquid Ge 1H1H33 x x x Galiquid Ge 1H1H31 x x x Galiquid Ge 1H1H31 x x x Asliquid Ge 1H1H32 x x x Asliquid Ge 1H1H31 x x x Asliquid Ge 1H1H31 x x x Asliquid Ge 1H1H31 x x x Asliquid Ge 1H1H31 x x x Asliquid Ge 1H1H31 x x x Asliquid Ge 1H1H31 x x x Asliquid Ge 1H1H31 x x x 10 6

28Managed by UT-Battelle for the U.S. Department of Energy Estimates of p-rich beam intensities with upgrades RIBTargetProd. BeamLimitAccelerated Beam Intensity (pps on target) (  A) HRIBF nowWith improved target design with C70 and improved targets 70 Seliquid Ge 4 He11 x x Seliquid Ge 4 He11 x x Seliquid Ge 4 He11 x x Seliquid Ge 4 He11 x x Seliquid Ge 4 He11 x x Cgraphite 1H1H158 x x Cosolid Ni 1H1H154 x x Nisolid Ni 1H1H152 x x 10 8

29Managed by UT-Battelle for the U.S. Department of Energy New Proton-rich Radioactive Beams (possible with increased energy, intensity, and reliability) 14,15 O from SiC or graphite targets – ( ,xn) reactions 21 Na from SiC targets using (p,2  ) reaction 29,30 P from Al 2 O 3, SiC, or CeS targets 30,31 S from SiC targets using 4 He production beams 33 Cl from CeS targets using 1 H or 2 H production beams 67,68 As from liquid Ge target – (p,3n) or (p,4n) reactions Long-lived isotopes (many possibilities) – Irradiate samples using the secondary proton beam – 68 Ge (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)