# Presentation: 536533

## Neutrino FactoryDesigns and R&D

- Steve Geer
- Fermilab

## Introduction

- Neutrino Factory  design concepts emerged in 1997-98 ... based on exploiting a muon collider like muon source.

- In recent years there has been significant interest in a new type of muon source  >> a millimole of muons per year  originally motivated by interest in Muon Colliders

- Since then: 2 design studies in US, one in Europe & alter-native design concept developing in Japan  Neutrino Factories feasible, but require hardware R&D.

- Will summarize the Neutrino Factory design options andprogress with the hardware R&D

- Steve Geer, Neutrino 2002

- May 2002

## US  -Factory Scheme

**Design Study 1** (completed April 2000)

**Design Study 2** (completed May 2001, based on upgraded BNL AGS )

- Proton driver:  Upgraded FNAL Booster

- Carbon target in 20T capture solenoid

- 50m decay channel (1.25T)

- Muon energy spread reduced using induction linac (phase rotation)

- Muons bunched at 200 MHz

- Transverse phase space reduced usingan ionization cooling channel

- Acceleration to 50 GeV in RLAs

- Achieved 6 x Study 1 muon rate >> 2 E20 useful   decays / year

- Hg jet target, better induction linac & cooling channel designs

- Steve Geer, Neutrino 2002

- May 2002

## CERN  -Factory Scheme

- Similar to US scheme but alternative technologies:

- Pion capture with magnetic
- horn

- Lower energy proton driver
- (2.2 GeV protons)

- RF for phase rotation (no induction linac)

- Transverse cooling channel
- With 44/88 MHz (not
- 200 MHz) RF cavities.

- Steve Geer, Neutrino 2002

- May 2002

## Japanese -Factory Scheme

- Japanese -Factory Scheme

- NO PHASE ROTATION OR COOLING
- (would benefit from some cooling)

- USE LARGE ACCEPTANCE
- ACCELERATORS - FFAGs

- R&D Issues:  RF, Injection/extraction,
- magnet design, dynamic aperture

- Proof of Principle
- (POP) FFAG
- tested at KEK in
- June 2000

**NEXT STEP**_ _
- 150 MeV FFAG
- Under construction
- At KEK

- RF R&D: US/Japan
- collaboration

- POP

_**GOAL**_**:  1.E20 >> 4.4E20 USEFUL muon**
**DECAYS / YEAR @ 20 GeV >> 50 GeV**

- Steve Geer, Neutrino 2002

- May 2002

## Proton Sources

- The starting point – a multi-GeV proton source providing an O(1 MW) beam on target.  **Everyone has a viable scheme:**

- CERN: 2 GeV SPL – 4MW

- Japan:  50 GeV, 0.8 MW JHF (upgrade to 4MW)

- BNL: Upgraded AGS24 GeV, 1-4 MW

- FNAL: Upgrade d Booster 8-16 GeV, 1-4MW

- NEUTRINO FACTORIES
- FIT ON EXISTING SITES
- & CAN USE UPGRADED
- EXISTING PROTON
- DRIVERS >> PLENTY OF
- CANDIDATE SITES

- 180 MeV H- linac

- Steve Geer, Neutrino 2002

- May 2002

## Producing Pions

- NEW BNL E910 pion production  Results
- Pion yields peak at few hundred MeV/c
- Data in fair agreement with MARS predictions (yields may be slightly higher than predicted)

- At constant proton beam power, pion yields vary slowly with proton energy >> broad range of proton driver energies can be considered.

- More particle production data in next few years from:
- HARP (CERN)
- Fermilab E907

- HARP

- Steve Geer, Neutrino 2002

- May 2002

## Target R&D for MW-Scale Proton Beams

- Carbon Target tested at AGS (24 GeV, 5E12 ppp, 100ns)
- Probably OK for 1.5 MW beam ... limitation: target evaporation

- Target ideas for 4 MW: Water cooled Ta Spheres  (P. Sievers), rotating band (B. King), conducting target,  Front-runner = Hg jet

- 13 Tesla

- CERN/Grenoble Liquid Hg jet tests in 13 T solenoid
- Field damps surface tension waves

- 0 Tesla

- BNL E951: Hg Jet in AGS beam
- Jet (2.5 m/s) quickly re-establishes itself.  Will test in 20T solenoid in future.

-          t = 0            0.75 ms          2 ms              7 ms            18 ms

- Steve Geer, Neutrino 2002

- May 2002

## Pion Capture – US Scheme

**US Design**: Target in ~20T capture solenoid which tapers down to 1.25T

- Steve Geer, Neutrino 2002

- May 2002

## Target Facility

- Need remote handling target facility – detailed design made for US neutrino factory studies 1 and 2.

- Based on SNS (Oak Ridge) design experience.
- Detailed radiation simulations (MARS, N. Mokhov) >> facility lifetime OK

- Steve Geer, Neutrino 2002

- May 2002

## Pion Capture - CERN

**CERN Design**:  Use 50 Hz magnetic horn
- (waist radius = 4 cm, I = 300 kA)

- Test horn (low current & rep. rate) almost completed  mechanical behavior

- Steve Geer, Neutrino 2002

- May 2002

## Reducing the  Energy Spread

**PHASE ROTATION**:  Drift followed by a time-dependent
- Acceleration (fast particles de-accelerated, slow accelerated)

- US Scheme: use 260m long (r = 95 cm) Induction Linac
- with internal 1.25T solenoid:  (p)/p = 55%  >>  4.4%

**2 m Section**

**Pulse system**

**Linac section**

- Steve Geer, Neutrino 2002

- May 2002

## Reducing the Transverse Phase Space

- Transverse phase space too large
- to fit within normal accelerator

- Must “cool” the beam fast –
- Before muons decay

- Electron cooling & stochastic
- Cooling too slow
- >> USE IONIZATION COOLING

- An ionization cooling channel
- Can be thought of as a LINAC
- Filled with material

**Need high gradient RF to keep**
**the muons captured**

- Coulomb scattering tries to heat beam

**Use Liquid Hydrogen absorbers**

**Use strong radial focusing**
**>> high field solenoid channel**

- Steve Geer, Neutrino 2002

- May 2002

## Cooling Channel Design

**Study**** ****2 Design**  (R. Palmer)

- 3.3 m long section

- RF:   17 MV/m  @  200 MHz

- Channel Length:  108 m

- High field solenoid :  3T >> 5T

- Lattice period: 5.4 m >> 3.3 m

- GEANT SIMULATION
-    RESULT (P. Lebrun)

- Solenoid radius:  33 cm >> 20 cm

- Liq. H      RF        Liq. H        RF       Liq. H

- 21 cm long Liquid hydrogen absorbers in high-field  solenoid with field reversing direction at absorber

- Steve Geer, Neutrino 2002

- May 2002

## MUCOOL RF R&D 

- _High Power 805 MHz Test Facility_12 MW klystron
- Linac-type modulator & controls
- X-Ray cavern
- 5T two-coil SC Solenoid
- Dark-current & X-Ray instrumentation

- Need high gradient cavities in multi-Tesla solenoid field

- Concept 1 – open cell cavity withhigh surface field

- Concept 2 – pillbox cavity - close aperture with thin conducting foil

- 805 MHz Cavity built & tested
- Surface fileds 53 MV/m achieved
- Large dark currents observed
- Breakdown damage at highest gradients
- Lots of ideas for improvement

- 805 MHz Cavity built & being  tested

- Steve Geer, Neutrino 2002

- May 2002

## MUCOOL Open Cell Test Results 

- Dark currents increase with accelerating field
- to the 10th – 15th power – understood within the framework of Fowler Nordheim field emission

- Cavity operated successfully at full power with B = 0T, and 2.0T.  Cavity damage stoppedoperation at 2.5T.

**R&D to improve****surface quality, reduce****dark current, suppress****breakdown planned &****beginning**

- Steve Geer, Neutrino 2002

- May 2002

## MUCOOL Pillbox Cavity Results

- 200 MHz cavity (factory) >> 17 MV/m  being designed >>  high power tests in ~ 2 years

- High power test cavity built  (LBNL, Mississippi)

- Operated at full power with copper foil and B = 0

- To be tested in multi Tesla field and with Be foil soon.

- Steve Geer, Neutrino 2002

- May 2002

## MUCOOL Liquid H2 Absorber R&D - 1

- Need thin windows to minimize scattering

- 330 m windows
- made (Mississippi)
- & measured (FNAL)

- Pressure tests performed (NIU) on 4 Windows including
- one at LN2 temp.

- FEA calculations give a good des-cription observedwindow deform-
- ation and rupture

- Steve Geer, Neutrino 2002

- May 2002

## MUCOOL Liquid H2 Absorber R&D - 2

- Must remove O(100) W heat deposited by dE/dx >>  good radial mixing

_**TWO CONCEPTS**_

**1.  Forced flow through nozzles:**
-        Prototype being built by University consortium       Flow pattern under study

**Driven  convection:**    Prototype being built by KEK  &  Osaka    Tested with Liq. Neon and heat deposited 	with wire array (low power) suggests 100W 	cooling OK    100W test planned

**Both absorbers will be filled with Liq. H2 **
**and tested at Fermilab**

- Steve Geer, Neutrino 2002

- May 2002

## New MUCOOL Test Facility

- Steve Geer, Neutrino 2002

- May 2002

## CERN Phase Rotation & Cooling

**2 MW amp.**

**88 MHz cavity**

- No Induction Linac – use drift + 44 MHz cavities
- for the phase rotation

- Cooling channel based on 44 MHz & 88 MHzcavities with some acceleration in middle

- 88 MHz High Power test at CERN this year

- Steve Geer, Neutrino 2002

- May 2002

## Cooling Experiment – MICE

**LOI for an International Cooling Experiment presented at PSI and Rutherford Lab**

**Rutherford Lab has put in place a project team**

- Single particle conceptdeveloped (most recently) at CERN.
- World Wide effort nowin progress to producea proposal towards theend of this year.
- Interested in collabor-
- ating ?
- US: D. Kaplan
- Europe: A. Blondel
- Japan: Y. Kuno

- Steve Geer, Neutrino 2002

- May 2002

## Muon Acceleration & Storage Ring

- After cooling, early acceleration with Linac,
- Later acceleration with RLAs

- SC  200 MHz cavity (Niobium sputtered on
- Copper) being built at CERN for tests at
- Cornell  15 MV/m

- Everyone has a muon storage ring
- design; they come in various shapes,
- but all have long straight sections

- Japanese Version

- 1.E20 useful muon decays / year

- 20 GeV/c

- Steve Geer, Neutrino 2002

- May 2002

## Conclusions

- Very active -Factory design & component prototyping in Europe, US, & Japan
- US studies have shown -Factory feasible aftera few years of R&D
- CERN & Japanese studies show alternative technology choices may be promising ... must be pursued until we are ready to make a choice
- Much interest in World-Wide collaboration in critical R&D areas .... but will need additional support !
- R&D pursued by Lab and University physicists ... particle physicists & accelerator physicists.

- Steve Geer, Neutrino 2002

- May 2002

## Food for Thought

- Neutrino oscillation physics is in a very exciting discovery phase and yet times are hard and R&D support for future neutrino facilities is being squeezed not expanded.
- We are making good progress with Neutrino Factory design & the R&D program  just had an excellent technical review.
- We have learnt how to get University groups & students very productively involved in the R&D and I suspect that this is the key to maintaining a healthy R&D program.
- If you want to learn more about how a University group that does not have an accelerator physics history can get involved in the R&D please let me know (_[sgeer@fnal.gov](mailto:sgeer@fnal.gov)__) and I will  tell you more._

- Steve Geer, Neutrino 2002

- May 2002