# Presentation: 520254

## Radioactive Ion Beam Development at the HRIBF

**Dan Stracener**
**S & T Review**
**November 22-23, 2004**

## Outline

**Highlights of Recent Accomplishments**
**Laser Ion Source**
**Photodetachment to purify ****56****Ni beams**
**Comparison of UC yields**
**New target preparation techniques (‘paint’)**
**HRIBF RIB Capabilities**
**Test Facilities (off-line and on-line)**
**Radioactive Ion Beam Intensities**
**ISOL Development Plans**
**New beams (****25,26****Al, ****30****P, ****33,34****Cl, ****11****C)**
**Efforts to improve beam quality (intensity and purity)**
**High power target development with the HPTL to achieve higher production rates in the target**

## Laser Ion Source Experiments (8/31/04 – 9/23/04)

**Laser ion source set up and operated at HRIBF in collaboration with a group from Mainz (Klaus Wendt and students)**
**Three-step ionization of Sn, Ge, and Ni obtained**
**Last ionization step: **
**autoionization state for Sn and Ge**
**No surface ionized Sn, Ge, and Ni ions observed**
**hot-cavity temperatures ~ 1700-2000 C**
**Overall LIS efficiencies:**
**20% for Sn (compared to 10% achieved at ISOLDE)**
**3% for Ge and Ni**
**Laser resonant ionization of Ga was observed**
**small signals on top of a large surface ion background**

## Laser setup for the initial test at the HRIBF

_**Laser setup for the initial test at the HRIBF**_

- Nd:YAG Pump laser
- (60 W, 10 kHZ, 532 nm)

- Ti:sapphire lasers
- (supplied by the
- Mainz group)

- Laser beam into the hot
- cavity through the
- mass-analysis magnet

## Sn Ionization Scheme

## Ni Ionization Scheme

## Ge Ionization Scheme

## Laser-induced Photodetachment of Niˉ and Coˉ in a He-filled RFQ Ion Cooler

**Neutralization: **
**           ****Co****ˉ****: ~95%**
**           ****Ni ˉ: ~10%**

-  Laser: Nd:YAG, 5 W, CW, 1064 nm
-  About 50% of laser beam passed through the RFQ (40 cm long)
-  The energy of the negative ions was reduced from 5 keV to <50 eV in the cooler
-  Laser interaction time in the RFQ cooler is on the order of 1 ms

## RIB yields from different UC targets

**Three UC target geometries tested**
**UC-coated RVC**
**low-density, highly porous carbon matrix (standard for HRIBF)**
**density is 0.6 g/cm****3**** to 1.2 g/cm****3**
**UC pressed pellets (ANL-O)**
**UOx powder mixed with C powder and converted at high temperature to UC (manufactured at ANL)**
**density is 2.5 g/cm****3**
**UC pressed pellets (ANL-C)**
**UC powder (manufactured at ANL)**
**density is 6 g/cm****3**
**The pressed powder pellets**
**Are significantly cheaper to produce**
**Need to be tested at high power**

## New Target Fabrication Technique

**New ‘paint’ technique to produce thin layer of target material on porous support matrix**
- make a very fine powder (~ 1 m dia.) of the target material
- suspend this fine powder in a liquid binder
- coat the support matrix with the paint using vacuum infiltration to draw the suspension into the internal surfaces
- dispersant is needed to prevent formation of aggregates and to allow penetration of ‘paint’ into the more dense matrices
- heat the target to about 850 C to drive off the binder, leaving a thin coating of the target material on the fibers
- has been used to make several targets (e.g. CeS, SiC, BN, HfC, ...)
**CeS has performed well**
**SiC has been tested with mixed results**
- the most recent test shows that the SiC powder was not tightly bound to the matrix
- solution: sinter at high temperatures in an Argon atmosphere

## UC targets using the ‘paint’ technique

- UC is uniformly distributed and tightly bound to the matrix
- On-line tests needed to compare release efficiencies to data from our standard UC/RVC targets (chemical deposition technique)
- Future targets will be made using higher density RVC matrices to increase the surface-to-volume ratio and thus increase the U density

## RIB Development and Testing Facilities

**Ion Source Test Facility I  (ISTF-1)**
**characterize ion sources (efficiency, longevity, emittance, energy spread, effusion)**
**some target tests (e.g. effusion through matrix)**
**ion cooler for negative ions (gas-filled RFQ)**
**Ion Source Test Facility II  (ISTF-2)**
**laser ion source**
**ECR ion source**
**On-Line Test Facility (OLTF)**
**low intensity tests of target and ion source performance**
**compatible with the RIB Injector and results are scaleable**
**Facility for preparing target/ion source modules for the RIB Injector (assembly and quality assurance)**
**High Power Target Laboratory (HPTL)**
**available in 2005 for target tests with high power beams from ORIC**

## Proton-rich Radioactive Ion Beams

- _Proton-rich Radioactive Ion Beams_

** ****Seven different targets used**
** ****Three different ion sources**
** ****14 radioactive beams**

- HfO2 for 17,18F beams

- CeS on RVC matrix for 34Cl

**Notes:**
F from hafnium oxide targets
Al from SiC target
Cu from a molten nickel target
As and Ga from a molten germanium target (hope to produce Se from this target using He-induced reactions)

## 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 | 100 |
| 17F | 10-170 | 1.0 x 107 | 3 | 100 |
| 18F | 10-108 | 6.0 x 105 | 1.5 | 100 |
| 67Ga | 160 | 2.5 x 105 | 5 | > 90 |
| 69As | 160 | 2.0 x 106 | 5 | ~ 10 |
| 70As* | 140 | 2.0 x 103 | 0.01 | < 10-6 |

*** This beam was used for commissioning of the RIB Injector**

## (over 110 beams with intensities 103 ions/sec)  

- _Available Neutron-rich Radioactive Ion Beams_
- (over 110 beams with intensities 103 ions/sec)

- E/A = 3 MeV/amu

## Accelerated n-rich RIBs (A<100 amu)

| RIB | Energy Range (MeV) | Highest Intensity (pps) | Purity (%) |
| --- | --- | --- | --- |
| 76Cu | 220 | 15 | 0.3 |
| 77Cu | 220 | 1.6 | 0.03 |
| 78Cu | 220 | 0.15 | 0.003 |
| 79Cu | 220 | 0.006 | 0.00012 |
| 78Ge | 175 | 1.5 x 106 | 67 |
| 80Ge | 179 | 1.8 x 106 | 95 |
| 82Ge | 183 - 327 | 1.8 x 104 | 22 |
| 83Ge | 220 - 327 | 1500 | 43 |
| 84Ge | 220 - 327 | 95 | 12 |
| 85Ge | 220 | 1.3 | 18 |
| 86Ge | 220 | 0.006 | 0.8 |
| 82Se | 380 | 4.7 x 105 | 78 |
| 83Se | 327 | 1.7 x 105 | 95 |
| 84Se | 327 - 380 | 1.1 x 104 | 10 |
| 92Sr | 450 | 500 | 72 |

## Accelerated n-rich RIBs (A>100 amu)

| RIB | Energy Range (MeV) | Highest Intensity (pps) | Purity (%) |
| --- | --- | --- | --- |
| 117Ag | 460 | 1.2 x 106 | 95 |
| 118Ag | 236 – 455 | 1.7 x 106 | 90 |
| 126Sn | 378 | 1.0 x 107 | 50 |
| 128Sn | 384 | 3.0 x 106 | > 99 |
| 130Sn | 391 – 550 | 5.0 x 105 | > 99 |
| 131Sn | 550 | 2.5 x 105 | > 99 |
| 132Sn | 316 | 8.6 x 105 | 96 |
| 132Sn | 453 – 620 | 1.5 x 105 | 96 |
| 133Sn | 316 | 1.7 x 104 | 33 |
| 134Sn | 316 – 560 | 2.8 x 103 | 38 |
| 136Sn | 400 | 3 | 0.2 |
| 129Sb | 400 | 2.9 x 107 | 49 |
| 132Te | 350 – 396 | 3.0 x 107 | 87 |
| 134Te | 396 – 565 | 2.4 x 106 | 95 |
| 136Te | 396 – 470 | 5.0 x 105 | 80 |

## Summary of Planned RIB Development

**Proton-rich beams**
**25,26****Al – proton scattering and transfer rates to better understand the ********-ray astronomy observations of ****26****Al**
**33,34****Cl – reaction rates that are important for nova nucleosynthesis**
**30****P – proton scattering and transfer rates to understand the large sulphur enhancements seen in novae**
**11****C – resonant scattering to investigate the low-lying states in ****12****N**
**56****Ni – nuclear structure in the ****100****Sn region; also proton capture is an important reaction in the rp process**
**17****F – higher intensities needed to measure the proton capture rates to better understand ****18****F production in novae**
**Neutron-rich beams**
**increase intensity by developing more robust targets and utilizing beam rastering techniques**
**increase beam purity by exploiting the differences in chemical behavior **
**Develop ion sources with higher efficiency and higher  selectivity**

## New Radioactive Beams

**25****Al, ****26****Al**
**Measured yields from three SiC targets (fiber, powder, and SiC coating on RVC matrix)**
**From measured yields, we expect about 10****4**** ions/sec on target**
**Need to determine limit of production beam power**
**Plan to investigate release rates from metal silicide targets (e.g. W****5****Si****3****) which have faster diffusion rates for aluminum**
**33****Cl, ****34****Cl**
**Measured yields using a thin layer of CeS on a RVC matrix**
**Expect about 10****4**** ions/sec of ****34****Cl**
**Need to investigate use of a negative ion source and determine the power handling capabilities of this target**
**11****C**
**Need to develop both the target and the ion source**
**Off-line tests to determine suitability of material (possibly BN/RVC)**
**On-line test to measure release rate**
**Plan to use LaB****6**** surface to make CN****ˉ (surface ionization)**
**56****Ni & ****17****F**
**efforts are underway to improve the quality (intensity and purity) of these beams**

## Enhancing Beam Purity

**Selective ionization techniques**
**surface ionization sources (depends on the temperature and work function of the surface)**
**LaB****6**** at 1100****°**** C ionizes halogens with efficiencies up to 25%**
**hot cavity of Ta or W at ~2000****°**** C can ionize alkaline elements with nearly 100% efficiency**
**laser ion source (useful for many elements)**
**Molecular formation, transport, and ionization**
**fluorides, chlorides, oxides, sulfides (e.g. SnS****+**** and GeS****+****)**
**aluminum for halogens (e.g. AlF****+****, AlCl****+****)**
**CO****+****, SeCO****+****, GaCl****+****, InCl****+****, SrF****+****, fluorides of refractory metals**
**Selective photo-detachment of contaminants**
**Ni****ˉ****/Co****ˉ****, Cl****ˉ****/S****ˉ****, F****ˉ****/O****ˉ**

## Goals of R&D at the HPTL

**To design and test targets that can withstand higher power densities**
**Develop target/beam overlap schemes to increase RIB production rates in the target**
**Increase the production beam current while maintaining the same power density**
**Larger target volumes**
**Beam rastering or defocusing**
**Implement and test new ion source designs in a realistic high-radiation environment**
**Develop targets that may be useful for RIA**** **

## Ion Sources to be used at the HPTL

**The target station and the RIB analysis beam line are designed to be flexible enough to accommodate a variety of ion sources**
**Electron-Beam Plasma ion source (EBPIS)**
**Kinetic Ejection Negative ion source (KENIS)**
**Laser ion source (LIS)**
**Positive surface ionization sources (hot Ta or W tubular ionizer)**
**Negative surface ionization sources (e.g. LaB****6**** ionizer)**
**Cs-sputter type ion sources (multi-sample, batch-mode)**
**Close-coupled designs (e.g. FEBIAD ion source – GSI design)**
**Electron Cyclotron Resonance (ECR) ion sources**
**Ion guide (cooler) techniques**

## Initial Tests at the HPTL (after commissioning)

**New Materials tests**
- SiC and metal silicides (e.g. Zr5Si3, Ta5Si3, Nb5Si3) for 25,26Al beams
- CeS for 33,34Cl and 29,30P beams
**New target geometries**
- Thin liquid Ge for 69As and p-rich Se beams
- Thin solids for use with 3,4He production beams
**Effect of rastering the production beam**
- Increase intensity of 17,18F beams from HfO2 (production beam presently limited to 3 A due to target damage)
- Important measurements to be made include 17F(p,)18Ne, 18F(p,)15O
- 17F Beam-on-target is 1 x 107 pps – need about a factor of ten improvement

**We need to significantly enhance the quality (intensity and purity) of the available proton-rich radioactive beams at the HRIBF.**

## A Possible Thin Target Geometry

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