# Presentation: 743207

## Simulations

**Simulations**
**in support of **
**RIA Target Area R&D**
**Reg Ronningen**
**NSCL/MSU**
**Igor Remec**
- ORNL

- 2nd High-Power Targetry Workshop
- October 10–14, 2005   Oak Ridge, TN** **

## RIA  R&D Participants(now starting 2nd year of funded effort)

- Argonne National Lab: J. Nolen, C. Reed, T. Levand, *I. Gomez*
- Lawrence Berkley National Lab: L. Heilbronn
- Lawrence Livermore National Lab: L. Ahle, *J. Boles,* *S. Reyes*, W. Stein
- Michigan State U./National Superconducting Cyclotron Lab: *I. Baek, V. Blideanu*, G. Bollen, D. Lawton, P. Mantica, D. Morrissey, R. Ronningen, B. Sherrill, A. Zeller
- Oak Ridge National Lab: J. Beene, T. Burgess, D. Conner, T. Gabriel, *I. Remec*, M. Wendel

**Notes:**
The names in italics denote the “ radiation field simulators” at each place, with special recognition to Susana Reyes for work presented here.

## Ronningen
Examples of Simulations for Fragment Pre-Separator Area Pre-Conceptual Design
Quadrupole radiation damage simulations
Beam Dump simulations
Bulk Shielding
Remec
Examples of Simulations for ISOL Target Area Pre-Conceptual Design
Two-step target simulations
Large-scale simulations examples

- Ronningen
- Examples of Simulations for Fragment Pre-Separator Area Pre-Conceptual Design
- Quadrupole radiation damage simulations
- Beam Dump simulations
- Bulk Shielding
- Remec
- Examples of Simulations for ISOL Target Area Pre-Conceptual Design
- Two-step target simulations
- Large-scale simulations examples

**Notes:**
Outline of talks

## A Sampling of RIA Primary Beams

- Current technology limits U to about 130 kW.
- All the rest are 400 kW.

**Notes:**
The RIA challenge is that beams of all stable elements are possible, and high energy and high power.

## Where Do Primary Beam and Fragments Go?

**Notes:**
The central ray shows the desired fragment. The other rays show where the the primary beam producing that fragment ends up. The challenge is to make pre-concepts of beam dumps and catchers.

## Sample Beam-Fragment Combinations

**Notes:**
Here note the very large beam power lost in the target and in the beam dump, for various beam fragment combinations.

## Target

- Beam Dump

- Quadrupoles

- Dipole

- Resistive Sextupole

- Simple Geometry of Fragment Pre-Separatorfor Simulations

- W Shield

- Developed using MORITZ Geometry Editor (White Rock Science)

**Notes:**
We have developed a simplistic fragment pre-separator geometry for our simulations. The materials, however, have realistic compositions.

## Transport of Primary Beam using PHITS

**Notes:**
This is the first test of the geometry when using the simulation code PHITS, having heavy ion and magnetic field capability. This is a track tally of 238U ions from the target, through the pre-separator, to the beam dump.

## Target

- Beam dump

- Steel shell surrounding system

- Resistive
- sextupole

- Neutron Flux in Pre-Separator using PHITS: 48Ca beam at 500 MeV/u

**Notes:**
This shows a tally on neutron flux in the pre-separator region, for a 48Ca beam having 500 MeV/u. Note the position of the beam dump. Note also, the dipole shape is modified to a “C-Magnet” shape.

## Target

- Hevimet shield

- Frames are cryostat walls
- HTS Coil: Ag+BSCCO
- Insulator: AlO+He

- “Realistic” Quadrupole Geometry
- using BNL Design with Realistic Material Compositions

**Notes:**
We made a more realistic model of the first quadrupole from a BNL design. Realistic material compositions were used (Coil and insulation examples given).

## Neutron Flux in Target, 1st Quad Area - No Magnetic Field

- Neutron Flux in Target, 1st Quad Area - No Magnetic Field

**Notes:**
This is a neutron flux tally, no magnetic field.

## Neutron spectrum at the coil for 136Xeat 500 MeV/u (PHITS simulation) 

**Notes:**
This is the neutron flux averaged over the coil cell (or region).

## Protons – no magnetic field

**Notes:**
This is a proton track tally with the field off. 

## Protons – Quadrupole magnetic field ON

**Notes:**
The proton tally with the field on. This is a “Y” quad.

## Total Heat Tally

**Notes:**
Note that the heating will be larger on the “X” poles because the “Y”-focusing quad de-focuses in “X”.

## Triplet heat – no magnetic fields

- Like the peak magnetic field determining the conductor requirements, the **maximum dose in a single area determines the coil life time**.
- Note the dose is a factor of two higher than calculations done for a single quad. This is because of the enclosure reflecting low energy neutron back into the coils.
- The **peak doses** on each subsequent quad is only reduced by a **factor of two** due to both the reflected neutrons and the high flux of very energetic ones  (>100 MeV).

## Using an average density of 10 g/cm3, 10 mW/cm3 

- Using an average density of 10 g/cm3, 10 mW/cm3
- give a dose rate of 1 Gy/s
- With 107 s per year operation, this is 10 MGy dose.
- If HTS is as radiation resistant as Nb3Sn (500 MGy),
- then coils last 50 years.
- Plan to test HTS 12/05 at LBNL with protons. It will be
- compared with Nb3Sn, which has known tolerance.

- Coil Life Estimate

## Advanced beam dump designs

- To mitigate radiation damage, rotating beam dump concepts are being considered
- In particular, a rotating barrel-shaped dump has been designed capable of withstanding a 1cm-diameter beam spot
- U beam stops in cooling water, avoiding high DPA values in structural material

**Need to address prompt and decay dose to sensitive components in rotating vacuum seal**

**Notes:**
From Susan Reyes’ talk on radiation damage, the collaboration was forced to look at non-static beam dump designs.

## Radiation transport results

- We have used the heavy ion transport code PHITS to simulate particle transport in pre-separator area
- Model includes barrel beam dump, steel water inlet/outlet pipes, hub region with representative materials and downstream multipole magnet

- Assumed operation with a 320 MeV U beam with 1 cm-diameter spot size at a current of 3x1013 pps

**Notes:**
The non-static components must be moved by motors, have water seals, special couplings etc.

## Vacuum enclosure and dipole included

**Notes:**
This is the geometry developed for this radiation damage calculation.

## Radiation transport results:            prompt dose and DPA

| Material | Density (g/cc) | Effective dose (MGy/yr*) | Dose limit (MGy) | DPA/yr* |
| --- | --- | --- | --- | --- |
| NdFeB | 6 | 0.29 | 0.1 | 4.5E-06 |
| SmCo | 8.82 | 0.15 | 100 | 5.9E-06 |
| Kapton | 1.42 | 0.74 | 10 | 7.6E-07 |
| FerroFluid | 1.42 | 1.08 | >1? | 7.1E-07 |

**Dose to ****NdFeB ****magnet exceeds recommended limit after ~ 2 months of full power operation****: shielding needed to extend lifetime**
**DPA in the hub materials found to be negligible**** **
**Maximum DPA rate in the Al barrel ~0.03 DPA/yr* (most of the primary beam stops in water); maximum DPA in multipole ~5x10****-4**** DPA/yr***
**Peak energy deposition in multipole = 0.03 W/cc, with 2.1 kW total**

- *Assumed that fragmentation line is operating at full power for one-third of the calendar year

## Borated (5 wt%) polyethylene shielding around NdFeB magnet(5 cm thick spherical shell)

| Material | Density (g/cc) | Effective dose (MGy/yr*) | Limit (MGy) |
| --- | --- | --- | --- |
| NdFeB | 6 | 0.05 | 0.1 |
| * Assumes operational for 1/3 of each year |  |  |  |

## 136Xe at 341 MeV/u, 3.74x1013 ions/sec

_**Simplified geometry model**_

- Water wheel dump with 3 mm Al window

- STST shaft containing water

- Sample materials outside concrete enclosure: LCS, FerroFluid, Kapton, SmCo

- Vacuum region enclosure (2 m thick concrete walls)

- AIR surrounding the whole system

- 136Xe at 341 MeV/u, 3.74x1013 ions/sec

**Notes:**
At MSU we did a similar investigation of LLNL’s rotating wheel concept, with similar results.

## Investigate Radioactivity Inventory for Components

**Notes:**
As did Susana, we calculated induced radioactivity in components for inventory, storage and waste purposes.

## Slide 25

**Notes:**
This compares the radioactivity in the water 90 days after the end-of-bombardment (for one month) by 136Xe, or 238U. Note the beam fragments and the contribution from alpha emitters in the case of the uranium beam. Information like this is important to know for maintenance and waste purposes.

## Proton, 3He, 238U Comparison

**U-238**** : ****400 MeV/u**

**He-3**** : ****777 MeV/u**

**proton**** : ****1 GeV**

- Beam on stopping Cu target

- Beam direction

**Notes:**
We are performing thick shielding calculations for RIA beams. Scoping calculations were performed. Note in this example that secondary particle radiation from heavy ions is sharply forward-focused.

## Compare Effective Dose Equivalentfor Different Beams

**Notes:**
The scoping calculations show we should concentrate design calculations around 3He and 22Ne, 48Ca beams.

## Results for Proton Beam and Concrete Shield

**Notes:**
This is an example of some first results. Similar simulations have been done for 3He, 22Ne and 48Ca beams and for 1,2,3 meter cast iron shielding.