# Presentation: 134199

## Rare Isotope Production at RIA

- RIA-Science
- Rare Isotope Production
- RIA Facility
**RIA target issues**
- Fragmentation targets
- Beam dumps
- ISOL targets
**Conclusion**

**Rare Isotope Production at RIA**

- G. BollenNational Superconducting Cyclotron Laboratory NSCLMichigan State University

**RIA – an intense source of rare isotope**

## Corner stones of the RIA Science Case

- The Nature of Nucleonic Matter
- The Origin of the Elements and Energy Generation in Stars
- Tests of the Standard Model and of Fundamental Conservation Laws
- Isotopes to Meet Societal Needs

## Nature of Nucleonic Matter  - Nuclear Structure

**Nature of Nucleonic Matter  - Nuclear Structure**

## Nature of Nucleonic Matter  - Binding Energies

- Masses and Trends in nuclear binding energies

- Limits of stability

- Key data for nuclear astrophysics

- Nuclear structure

## How were the heavy elements from iron to uranium made? 

- Question: Is this difference due to shell quenching for neutron-rich nuclei, or a problem with astrophysical model?

- Pfeiffer & Kratz, Mainz

- A

- relative abundance

**How were the heavy elements from iron to uranium made? **

## Tests of the Fundamental Symmetries in Nature

- Specific nuclei offer new opportunities for _precision tests of:_
-  CP and P violation – baryon asymmetry in the Universe
- Standard Model_ Tests:_
-  Unitarity of CKM matrix
-  Physics beyond V-A
-  sin2W at low q

## Applications of nuclides from RIA

- Development of techniques and manpower for dealing with radioisotopes.
- Stockpile stewardship – allow measurements of necessary cross sections to insure the reliability of simulations.
- Allow testing of new radioisotopes for medicine.
- Tracers for various studies.
- Soft doping, etc.

- Workshops at Los Alamos and Lawrence Livermore Labs

## Goal: one facility for most of the key nuclei

- r-process

- drip line nuclei

- RIA

## Recipe: Combine Production Mechanisms

- Fragment Separator

- Gas stopping

- Post
- Acceleration

- Driver Accelerator

- Fragment Separator

- High Resolution Separator

**ISOL**

- Gas-Stopping

**In-Flight**

- Target

**NEW**

## ISOL -  In-Flight  -  Gas Stopping

- Post-accelerated beams with small beam energy spread for fusion studies and nuclear astrophysics
- Can use chemistry and selective laser-ionization to limit the elements released
- Production targets optimized for element and isotope

**ISOL ****-****  ****In-Flight****  ****-****  ****Gas Stopping**

- Provides beams with energy near that of the primary beam
- For experiments that use high energy reaction mechanisms
- Thick secondary targets, kinematic focusing
- Individual ions can be identified
- Efficient, Fast (100 ns), chemically independent separation
- Capture in storage rings
- Production target is relatively simple

- _In-flight:_
- _GSI_
- _RIKEN_
- _NSCL_
- _GANIL_

- _ISOL:_
- _ISOLDE _
- _HRIBF_
- _ISAC_
- _..._

- _Gas-_
- _Stopping:_
- _ANL_
- _MSU_
- _RIKEN_

- Beams from in-flight production
- Chemically independent
- Intensity limits – half-life limitation    still to be studied

## Optimum production
method for low-energy beams

          Standard ISOL technique          Two-step fission ISOL          In-flight fission + gas cell          Fragmentation + gas cell

**Optimum production**
**method for low-energy beams**
-           Standard ISOL technique          Two-step fission ISOL          In-flight fission + gas cell          Fragmentation + gas cell

**Optimum Mechanism for Each Isotope**

**Worldwide Unique Feature**most other facilities have only one production mechanism

- +** Fast beams with high intensities**

## Rare Isotope Accelerator - RIA

-  _Most intense source of rare isotopes_
-  **High power primary beams** protons to U at 100 kW and E > 400 MeV/nucleon.
-  Possibility to **optimize the production method** for a given nuclide.
- _ __Four Experimental Areas (simultaneous users) _

## Towards realizing RIA

- R&D work going on (Accelerators, Sources, Targets, ...)  (DOE + local)
- 			*RIA R&D Workshop Washington August 2003*
- Layout options under study at ANL and MSU

**2 Fragment separators**
**Fast beam**
**Gas stopping**
**2 ISOL stations ******** 3 ****in latest MSU layout**

## RIA Layout

**MSU August 2003**

## Driver Linac Beam Parameters

| Ion | A | Q | IECR(pA) | 
Efinal/A(MeV) | Final Beam Power (kW) |  |
| --- | --- | --- | --- | --- | --- | --- |
|  |  |  |  |  | 1 charge state | 2 charge states |
| H | 1 | 1 | 540 | 1019 | 400 | - |
|  Xe | 136 | 17 | 12 | 470 | 400 | - |
| Au | 197 | 23+24 | 5.5 |  | 241 | 483 |
| U  | 238 | 28+29 | 1.5 | 400 | 77 | 154 |

- Beams from protons to Uranium
- Beam power up to 400 kW or more

## Beam distribution to targets

- Accommodate target area developments & to increase flexibility
- 100% to any one, 50%/50% to any two, 50%/25%/25% to any three, 25%/25%/25%/25% to any four
- Even more flexible power and beam distribution desired for best RI production

## Fragmentation Area Layout

- Productions Targets
- Very high power density - ~ 4 MW/cm3
- Small spot size – reduce geometric aberrations
- ~20% of beam power lost in target
- Beam dumps
- medium spot size, high power density ~ 50 kW/cm3 , not localized
- High performance & radiation resistant magnets required – R&D challenge
- Characterization of radiation fields – required to support R&D efforts

## High power fragmentation targets

**High power fragmentation targets**

- Rotating carbon target for up to 100 kW beam power (RIKEN)

**Solid targets**

- T. Kubo, NIM B204 (2003)97
- A. Yoshida et al, RIKEN Accel. Prog. Rep. 35 (2002) 152

- Li-cooled Be target for 4 kW beams at the NSCLANL – MSU development

- J.A Nolen et al., NIM B204 (2003) 298

-  talk by J Nolen

## High power fragmentation targets

- Windowless liquid metal targets
- ANL – development

- J.A Nolen et al., NIM B204 (2003) 293

-  talk by J Nolen

-   Very high power density - ~ 4MW/cm3
-   Small spot size – reduce geometric aberrations
-   ~20% of beam power lost in target
-  Development of targets for lighter beams required !

## Fragmentation beam dumps

- 80% of initial beam power goes into dump Range of U (400 MeV/A)  5 -10 mm (C - Cu)

- Unreacted primary beam ....

- Typically a few kW beam power

- NSCL A1900 beam catcher-bar for 4 kW

- ... and unwanted secondary ions

- Needs R&D

## ISOL beam production

- Basic Scheme:

**Realized at ISOLDE, HRIBF (<10 kW),  ISAC (<50kW)**
**Planned for RIA (400 kW), EURISOL (100kW + 4 MW)**

-  H. Ravn, R. Bennet

- ISOL target/ion source development has happened since > 30 years
- More elements
- Shorter release and higher yields,
- Higher selectivity and efficiency
- Higher power

## ISOL beam production at RIA

- 3 ISOL stations with pre-separators
- 400 kW capability
- Staged realization likely
- 2 high resolution mass separators
- 2 experimental areas
- Stopped beam experimental area
- Post-accelerated beams

**R&D issues target area**
- Targets + beam dumps
- Remote handling
- Classification

## ISOL Target station

-  400 kW ISOL station:
-  Vertical vs horizontal system, shielding, how many stations
-  Remote handling - fast target changes – lifetime of components
-   ...
- Needs more detailed design studies and R&D -  **Now!**

## ISOL targets for RIA

**Targets for spallation reactions**
- Metal foil targets(RIST/ISOLDE, J. Bennet, P. Drumm, H. Ravn, ISAC, P. Bricault, M. Dombsky)
- Oxide-Fiber targets, Composite targets (ORNL, ISOLDE)
- ...
**Production of fission isotopes**
- 2-step UC targets with neutron converters(ISOLDE, ANL, ORNL)
- Targets for Heavy Ion Beams

- High power capability
- Short release times
- High efficiencies

## Metal foil targets

- ISAC Ta foil target for 50 kW beam

- P. Bricault et al, NIM B204 (2003) 219

- RIST target: Ta foil target
- 100 kW beam power (30 kW dissipated)

- J.R.J Bennet et al, NIM B126 (1997) 105

- Radiation cooling good at high powers ( T4)
- Max. 450 W/cm2 at 3000 K
- Realistic: 30 W/cm2 at 2000 K
**Which cooling schemes at higher beam power?**

## Targets for fission products

**Principle of 2-stage targets:**
- Neutron converter for neutron production and dissipation of beam power
- Surrounding blanket of fissionable material

- In use at ISOLDE  H. Ravn

- RIA R&D:
- Prototype for ISAC (50 kW)
- Full system under study for RIA     ANL-Techsource-ORNL
-      J. Nolen

- Li cooled Tungsten converter

- UCx blanket

- Low beam powers: protons on UCx target matrix

- ANL concept

## Alternative: Mercury converter targets

- EURISOL
- Neutrino beam development
-  H. Ravn

- www.ganil.fr/eurisol/

- Window-less or window version?

**Benefit from SNS work**

**Key advantages of Mercury **
- -         It remains liquid which eases target changes and handling
- -         It is not flammable, which is a decisive safety point
- -         Increased potential for isotope recovery
- ...

## Status of RIA – Targetry 

- R&D has started but it is at its very beginning
- 100 kW concepts appear realistic
- It remains open which  > 100 kW targets can be built and how they will look like
- Continue with present R&D – get and follow new ideas
- Benefit from R&D at other RI facilities, spallation neutron sources, neutrino beam facilities, ...
- Important at early stage:
- consider impact of possible target options including remote handling, safety etc
- Make a flexible and expandable layout of RIA

- This workshop !

## ISOL target development for RIA – a wide field

**ISOL target development for RIA – a wide field**

- Evaluation of** Cooling schemes**
**Material research: **experimental tests of known and new materials for targets and target containers
- Considering **target options** – solid or liquid metal converters?
- Further development of codes for the **modeling** of target issues
- Design of **prototype targets**
**Power tests,** study of **release times** of prototype targets and **yield** measurements
**...**
**Develop tools** that can help to make target development more efficient

- High power issues

- Production and release

- ISOL target R&D

## ISOL target development with fragment beams

- Implantation of practically any isotope into target materials, target systems, prototypes ...
- Localized implantation
- Tests very close to realistic conditions if target heated
- Low radiation level and radioactivity build up – **Hands-on** experiments - Fast iterations

- NSCL fast RI beams
- (100 MeV/u)

**Proposed scheme**

- Not a replacement of on-line tests but will help to do fast prototyping

## Scenario for an ISOL test station at the NSCL

- Flexible front end design for mounting different types of targets
- Mass separator with modest resolving power
- Counting station for RI identification
- Rotation and translation degrees of freedom

## ISOL R&D opportunities with fragment beams

- Diffusion and effusion studies (different materials, geometry and temperature)
- Investigation of formation of molecular sidebands (*C + TaO = Ta + *CO, *S + Sn = Sn*S, *Si + CeS =  *SiS + Ce, *O + C = C*O, or *Al + F = *AlF)
- Disentanglement of long-term effects of temperature and radiation damage on target performance
- Test of RIA target prototypes
- Test of targets used or under development at other ISOL facilities

**Examples:**

## ISOL R&D opportunities with fragment beams

- Low-power primary beam + fragmentation targetor beam from fragment separators
- Catchers optimized for fast release
- Not a primary production scheme for RIA, but may enhance facility output

**ISOL R&D opportunities with fragment beams**

**Fast beams can become a valuable tool for ISOL R&D**

- starting at the NSCL and continuing at RIA

## Importance of Nuclear Physics in the r-process

- _Need to determine experimentally_:
-  Are shells reduced far from stability?
-  Are the astrophysical models wrong?
-  What does the abundance distribution tell us about the site?

****** ****post-processing****signature ?  **

- Shell gap reduced

- Full shell gap

- In r-process model calculations shell structure affects the results.

**Importance of Nuclear Physics in the r-process**

- Abundance

- A

## Energy Dependence of RI Production: RIA Example

- The turn over point depends on the fragment separator acceptance.
- A smaller acceptance fragment separator produces a later turnover.

- J.R.J Bennet et al, NIM B126 (1997) 105

## RIA Science Case

**Nature of Nucleonic matter**
**Origin of the Elements**
**Tests of the Fundamental Symmetries of Nature**
**Isotopes for Applications**