# Presentation: 801461

## Considerations on Proton Driver Parameters for a Neutrino Factory

-                          W. T. Weng
-          Brookhaven National Laboratory
-                International Scoping Study
-              KEK, Japan,  Jan/23-25, 2006

## Collaborators

- J. S. Berg, R. Fernow, H. Kirk, N. Simos,
- W. Weng, BNL; M. Zisman, LBL;
- S. Brooks, RAL
-                       Acknowledgement
- W. Chou, FNAL; D. Raparia, BNL

## Outline

-  Motivation of this study
-  Examples of parameter dependence
-  Possible design parameter phase space
-  Comparative merit of various approaches
-  Future R&D
-  Summary and Conclusions

## Motivations for This Study

- Understand the impacts and constraints imposed
-     by downstream sub-systems
- Identify possible design parameter phase
-     space of the Proton Driver
- Comparison of Linac, RCS, FFAG, and LAR
-     configurations
**This is a progress report to be completed in May**

## Considerations of parameters - I

- To deliver 4 MW beam power on target,
- we consider the effects of
- Energy
- Repetition Rate
- Intensity
- Bunch Length
- Of the Proton Driver

## Consideration of Parameters - II

- We evaluate their impacts on
- Target
- Muon Collections and Conditioning
- Muon Acceleration
- Muon Decay Rings

## Proton per pulse required for 4 MW

|  | 10 Hz | 25 Hz | 50 Hz |
| --- | --- | --- | --- |
| 10 GeV | 250 × 1012 | 100 × 1012 | 50 × 1012 |
| 20 GeV | 125 × 1012 | 50 × 1012 | 25 × 1012 |

## Stephen Brooks’ Analysis with MARS15

- Pions counted at rod surface
**B**-field ignored within rod (negligible effect)
- Proton beam assumed parallel
- Circular parabolic distribution, rod radius

- 20cm

- 1cm

- Solid Tantalum

- Protons

- Pions

## Yield of ± and K± in MARS

- No surprises in SPL region
- Statistical errors small
- 1 kaon  1.06 muons

**Finer **
**sampling**

## Phase Rotator Transmission

- Transmission from GEANT4 is a lot higher (×2) because it tends to forward-focus the pions a lot more than MARS15

- Energy dependency is much flatter now we are selecting pions by energy range

- Optimum moves down because higher energies produce pions with uncapturably-high momenta

## The Study2 Target System

-    Analysis I
- Count all the pions and muons that cross the transverse plane at z=50m.
- For this analysis we select all pions and muons with KE< 0.35 GeV.

## Process mesons through Cooling

-    Analysis II
-     Post Cooling
- Count mesons within
- acceptance of 30π mm

## Post-cooling  30π Acceptance

## Summary

- For Negatives the peak occurs for
-       6 Gev < Proton KE < 11 GeV
- For Positives the peak occurs for
-       9 Gev < Proton KE < 19 GeV
**Consensus:   10 GeV is a good place to be**

## Blackbody Radiation Stripping 

**Energy Dependence**

**Temperature Dependence**

**At 305 K (90 F) and 8 GeV, H******** ****loss rate = 0.8 ******** 10********6****   m********1**** **

## Summary of H Stripping Losses

- Transport line ~ 1 km  Loss on the beam line ~ 103
- H Beam intensity = 1  1014 s1   Loss rate ~ 108 m1s1
- At 8 GeV  0.13 W/m
- When MI operates at lower energy *E* with same beam power, loss will increase:

## Energy Dependence of H(0) Yield

**8 GeV, 0.5% H****0**

## Pulse Length Effects on Solid Targets

| 
  1 MW/50 Hz
  12.0 e+12 ppp
 | 
  4 MW/50 Hz
  48.0 e+12 ppp |
| --- | --- |
| 
  1 MW/200 Hz
  3.0 e+12 ppp | 
  4 MW/200 Hz
  12.0 e+12 ppp
 |

- Of interest is the pulse length assessment  for the following
- power, rep-rate and consequently pulse intensity combinations

## Target/Beam Baseline used for comparison

## 1 MW Proton Driver - Temperature IssuesPower and Heat removal capacity from target go hand-in-hand 

## 1 MW/50 Hz PD – Shock Stress Effects

## 1 MW/50 Hz PD –  target peak stresses3ns – 30ns – 300ns – 600ns

- 1 MW/50 Hz PD –  target peak stresses3ns – 30ns – 300ns – 600ns

## 4MW/50 Hz Proton Driver – Effect of pulse length on target peak stresses[3ns – 30ns – 300ns – 600ns]

**Solid target CAN support a proton driver operating  **
**      ****at 1MW with 50 Hz  rep-rate**
**Solid target CAN operate at 1MW at all pulse length**
**Solid target CANNOT operate at 4MW/50Hz,**
**       ****even with 600ns.**
**Liquid target has fewer such constraints(P, L, F)**
**      ****Modified solid Target design( non-stationary,..)**

## SUMMARY of Performance

| 
  1 MW/50 Hz
 12.0 e+12 ppp
     YES | 
  4 MW/50 Hz
 48.0 e+12 ppp
   NO |
| --- | --- |
| 
  1 MW/200 Hz
 3.0 e+12 ppp
   YES
 | 
  4 MW/200 Hz
 12.0 e+12 ppp
  MAYBE |

## Design Parameter Phase Space

- 8.0 GeV < Energy < 20.0 GeV
- Rep Rate ~ 50(25) Hz
- Intensity 50*10**(12) ppp, at 10(20) GeV
-       ( very difficulty with solid target )
- 4.   Bunch Length < 3 ns, for longitudinal
-                                           acceptance
- 5.   Cost ???

##  Technology Matrix*(Picture will change after R&D)

|  | Linac | RCS | FFAG | LAR |
| --- | --- | --- | --- | --- |
| Energy |  B |  A |  A | A |
| Rep Rate | A | A | A | A |
| Intensity | A | A | B_ | A |
| Bunch L | C | B | B_ | B |
| Cost | B_ | B | B+ | B_ |

## Accelerator/Target R&D Needed

- Generation of intense short bunch
- Optimal design of a proton linac
- Development of liquid target
- More study of the production of Pions and Muons
- Better understanding of impact on cost by the parameter choice

## Summary and Conclusions

- We have presented the parameter constraint
-     for the Proton Driver
- A preferred parameter phase space has been
-     identified and relative merit of each technology has been evaluated
- Further study is need to complete the search
-    and more R&D is needed for a reference design