# Presentation: 485305

## Target & Capture for PRISM

- Koji Yoshimura
- On behalf of PRISM Target Group
- Institute of Particle and Nuclear Science
- High Energy Accelerator Research Organization
-  (KEK)

## Contents

- Targetry for PRISM
- Solenoid capture
- Conducting Target
- Summary

## What’s PRISM

- PRISM( Phase Rotation Intense Slow Muon source)
- A dedicated secondary muon beam channel with high intensity (1011~1012/s)and
- narrow energy spread(a few%) for stopped muon experiments

- Pion Capture

- FFAG
- PhaseRotator

- Sensitivity ~100 x MECO

## Requirements of Targetry for PRISM

- Pion Momentum
- ~100 MeV/c
- backwards capture scheme available!
- Emittance
- As low as FFAG acceptance
- horizontal 10000vertical 3000
- Method
- Solenoid Capture
- Conducting Target

## Simulation Study of Solenoid Capture

- Simulation code
- MARS, GEANT3
- 12 T field -> 3T
- 47MeV/c ~ 85 MeV/c
- Backward
- 2000  ~ 3000  vertical acceptance

- proton

- 12 T

- 3 T

## Simulation Results

- Target material
- W is better than C
- B field
- Determined by Capture field
- YieldBfield
- Target radius
- Thin target is better

- C

- W

- C

- W

- B Field

- Radius(cm)

- Length

- Bore ()

## SC Solenoid in High Rad. Env

- Thick radiation shield is necessary
- ~500 W
- Radiation shield of 25 cm in thickness is needed
- Large bore for absorber
- High stored energy
- Expensive magnet
- To optimize design
- We totally rely on simulation.
- Simulation code should be experimentally evaluated!

- Absorber

- SC Coil

- Thickness of Absorber

- 25 cm, 500W

## Direct Measurement of Radiation heat by Beam

- Prototype magnet of 10.9 Tesla
- Hybrid coil (NbTi, Nb3Sn, HiTc)
- Indirect cooling with GM cryocooler
- 10.9 T in 6 cm warm bore
- Beam test with Coil-Mockup
- Direct measurement of heat load by radiation
- Study behavior of magnet under heating condition
- KEK 12 GeV proton
- 1011 protons/s
- Cryo-calorimeter

- Ohnishi's Talk

- Prototype magnet

- Temperature rise by radiation heat

- Beam test at KEK Nov, 2002

## Comparison

| B | 12 T | 6 T |
| --- | --- | --- |
| Useful aperture R | 0.05 | 0.10 |
| Cryost. IR | 0.55 | 0.4 |
| Coil IR | 0.65 | 0.45 |
| Coil OR | 1.1 | 0.55 |
| Coil length | ~1.6 | ~1.6 |
| S/C | Nb3Sn/NbTi | NibTi |
| Stored energy | ~190 MJ | ~16 MJ |
| Coil mass | ~20 Ton | 2 Ton |
| Cost (Estimate)* | ~17 M$ | ~3 M$ |

- *PDG: COST(in M$)=0.523[E/1 MJ)]0.662

## REALISM

- Baseline option
- B=6T
- IR=450 cm, L=160 cm
- Graphite Target  L=2λ=80 cm
- Shield thickness 25cm
- Still Necessary for R&D
- Cooling ~500 W
- Quench protection
- Radiation safety
- Thin Graphite target

## Further R&D Planof PRISM Solenoid option

- R&D Coil will be constructed this year
- Half or Quarter size
- Heating using AC LOSS
- Or Special heater
- Cooling Method ~500W
- Pool boiling
- Thermo siphon (Using convection)
- Proto-type of graphite target
- JHF neutrino group (Hayato, Oyabu et.al)
- Water cooled graphite (40 kW heat)
- Thinner Target?
- Engineering Design -> Future Upgade

## Conducting Target

- Confine pions inside the target with troidal field
- B. Autin, @Nufact01
- Advantage over Solenoid
- Low emittance beam
- Linear transport element
- No SC solenoid channel
- Cheaper!
- Cooling condition better?

## Comparison of target material

- Mercury is good candidate
- Minimum Power
- Easy to cooling
- Higher pion yield
- Technical Issues
- How to cut off electrical circuit?
- Stress due to pinch effect
- Container
- Shockwave
- Cavitation
- Thicker wall can be used!
- No reabsorption
- Window

- B. Autin et al.

## Setup for current test

- 1st phase
- 1000 A DC
- 100 J
- 2nd phase
- 250 KA 2.5ms Pulse (K2K horn PS)
- 15 KW
- 3rd phase
- 1 MW?
- Beam test?

## Mercury Test Loop

- Mercury 18 litter ~ 250 kg
- Study mercury flow

## Summary

- Solenoidal Capture
- Standard scheme
- Beam test was successfully performed using the mockup
- Design parameters will be considered.
- Realistic R&D Model coil
- Conducting Target
- merits
- R&D Work has just started!
- Proof of principle
- Feasibility test of High current liquid target

## Basic Priciple 

- (Inside the target)

- Proton

- Acceptance

- B. Autin et al.