Rencontres du Viet-Nam 2004 Alain Blondel Challenges of future accelerator-based Neutrino Facilities Introduction Proton drivers Target and Collection

Rencontres du Viet-Nam 2004 Alain Blondel

Challenges of future accelerator-based Neutrino Facilities

Introduction

Proton drivers Target and Collection Neutrino Factory challenges muon cooling acceleration (FFAGs) Beta-Beam challenges

See NUFACT04 site: http://www-kuno.phys.sci.osaka-u.ac.jp/~enufact04/http://muonstoragerings.cern.ch


1. We know that there are three families of active, light neutrinos (LEP)2. Solar neutrino oscillations are established (Homestake+Gallium+Kam+SK+SNO+KamLAND)3. Atmospheric () oscillations are established (IMB+Kam+SK+Macro+Sudan+K2K)

4. At that frequency, electron neutrino oscillations are small (CHOOZ) This allows a consistent picture with 3-family oscillations ~300 m12

2~8.5 10-5eV2 ~450 m23 2~ 2.5 10-3eV2 ~ 100 with several unknown parameters mass hierarchy

Where are we?

*)to set the scale: CP violation in quarks was discovered in 1964 and there is still an important program (K0pi0, B-factories, Neutron EDM, LHCb, BTeV….) to go on for >>10 years…i.e. a total of >50 yrs.

and we have not discovered leptonic CP yet!

5. LSND ? ( miniBooNe) This result is not consistent with three families of neutrinos oscillating, and is not supported (nor is it completely contradicted) by other experiments.

If confirmed, this would be even more exciting See Barger et al PRD 63 033002

Where do we go? leptonic CP & T violations=> an exciting experimental program for at least 25 years *)


Atmospheric “wavelenght”


Road Map

A Experiments to find : search for e

--in conventional beam (MINOS, ICARUS/OPERA) limitations: NC background, intrinsic e component in beam -- in reactor experiments --Off-axis beam (JHF-SK, off axis NUMI, off axis CNGS) or --Low Energy Superbeam (BNL Homestake, SPL Fréjus)

B Precision experiments to find CP violation -- or to search further if is too small

-- beta-beam and

-- Neutrino factory with muon decay storage ring

and

fraction thereof will exist .

eνLiHe e66 eνFNe e

9181018

μe ννeμ μe ννeμ


Example: a series of facilities envisaged for CERN

As always in neutrino physics the event rate is a major concernMost future facilities are based on a High Intensity Proton source.


300 MeV Neutrinos

small contamination from e (no K at 2 GeV!)

A large underground water Cerenkov (400 kton) UNO/HyperKor/and a large L.Arg detector. also : proton decay search, supernovae events solar and atmospheric neutrinos. Performance similar to J-PARC IIThere is a window of opportunity for digging the cavern stating in 2008 (safety tunnel in Frejus)

CERN-SPL-based Neutrino SUPERBEAM

Fréjus underground lab.

target!


-- Neutrino Factory -- CERN layout --

e+ e

_

interacts

giving

oscillates e

interacts giving

WRONG SIGN MUON

1016p/s

1.2 1014 s =1.2 1021 yr

3 1020 eyr

3 1020 yr

0.9 1021 yr

target!cooling!

acceleration!


CERN: -beam baseline scenario

PS

Decay

RingISOL target & Ion source

SPL

Cyclotrons, linac or FFAG

Decay ring

B = 5 T

Lss = 2500 m

SPSECR

Rapid cycling synchrotron

Nuclear Physics

,

Same detectors as Superbeam !

EU pride..

target!

Stacking!


Nuclear and ParticleExperimental Facility

Materials and Life ScienceExperimental Facility

Neutrino to Kamiokande

Linac(350m)

3 GeV Synchrotron(25 Hz, 1MW)

Nuclear Transmutation

The reference facility: J-PARC 0.75 MW at start, evolving

50 GeV Synchrotron(0.75 MW)

J-PARC = Japan Proton Accelerator Research Complex


Fermilab Proton Driver8 GeV Superconducting Linac

Basic concept inspired by the observation (by Bill Foster) that $/GeV for SCRF has fallen dramatically Consider a solution in which H- beam is accelerated to 8 GeV

in a superconducting linac and injected directly into the Main Injector

Attractions of a superconducting linac: Many components exist (few parts to design vs. new

synchrotron)Copy SNS, RIA, & AccSys Linac up to 1.2 GeV“TESLA” Cryo modules from 1.2 8 GeV

Smaller emittance than a synchrotronHigh beam power simultaneously at 8 & 120 GeV

Plus, high beam power (2 MW) over entire 40-120 GeV rangeFlexibility for the future

IssuesUncontrolled H- stripping Halo formation and controlCost


Fermilab Proton Driver8 GeV SC Linac: Other possible missions (from the mind of Bill Foster)

~ 700m Active Length8 GeV Linac

X-RAY FEL LAB

Long-Pulse Spallation Source

8 GeVneutrino

MainInjector@2 MW

Anti-Proton

SY-120Fixed-Target

Neutrino“Super- Beams”

NUMI

Off- Axis

& Neutrino Target

Neutrinosto “Homestake”

Short Baseline Detector Array

Target and Muon Cooling Channel

Bunching Ring

RecirculatingLinac for Neutrino Factory

VLHC at Fermilab

Damping Ringsfor TESLA @ FNALWith 8 GeV e+ Preacc.

1% LC Systems Test


High intensity proton accelerators pose many challenges but certainly one of the most critical one is the

Target !

Typical Dimensions: L 30 cm, R 1 cm

4 MW of protons (i.e. 40 000 light bulbs!)

into a big cigar….

it would immediately go to smoke.


Liquid Mercury Target R&D

Experiment @BNL and @CERN

Speed of Hg disruptionMax v 20 m/s measured

v// 3 m/s

(design calls for 20m/s)

Protons1 cm

liquid jet of mercury

jet remains intact for more than 20 microseconds.


A. Fabich et al– CERN-BNL-Grenoble

US scheme: jet is inside a

very high field tapered solenoid

(20 T max)

this was tested at the Laboratoire de Champs Intenses (Grenoble)

Liquid Mercury Target R&D


Proposed rotating tantalum target ring

Targetry: other ideasMany difficulties: enormous power density

lifetime problems

Replace target between bunches:

rotating solid target

Stationary granular target:

Densham Sievers


Target & collection

2.2 GeV4 MW

Protons

Current of 300 kA

B1/R

B = 0

The CERN magnetic horn for pion collection

Prototype built at CERN

Major issue is resistance of horn material to combination of shock, Joule heating & irradiation


Participating Institutions1) RAL2) CERN3) KEK4) BNL5) ORNL6) Princeton University

Proposal to test a 10m/s Hg Jet in a 15T Solenoid with an Intense Proton Beam

Target & collection

aim:Installation and commissioning

at CERN by April 2006


Hg-jet system

Power absorbed in Hg-jet 1 MW

Operating pressure 100 Bar

Flow rate 2 t/mJet speed 30 m/sJet diameter 10

mmTemperature

- Inlet to target 30° C- Exit from target100° C

Total Hg inventory 10 tPump power 50

kW


Muon ionization cooling

principle reality (simplified)

Never realized in practice !A realistic prototype should be built and proven to be adequate to the Neutrino Factory requirements.

reduce pt and pl

with as little heating as possible: Hydrogen!

increase pincrease pll

fast fast accelerationacceleration

Frictional cooling is only for +

A novel method for + and - is needed: ionization cooling


MICE setup: cooling + diagnostics


Operation of RF cavities at high gradient in magnetic

field

Dark current backgrounds measured on a 805 MHz cavity in magnetic field!with a 1mm scintillating fiber at d=O(1m)

This will be also a source of backgrounds for MICE:


RF cavity (800 MHz) at Fermilab being pushed to its limits (35 MV/m)to study dark current emission in magnetic field. Sees clear enhancement due to B field. Various diagnostics methods photographic paper, scintillating fibers Microscope ------ BCT and solid state counters have demonstrated this and allowed precise measurementsReal cavities will be equipped with Be windowswhich do not show sign of being pitted contrary to Cu


MICE cooling channel R&D

LH2 window(IIT, NIU, ICAR)

RF module(Berkeley, Los

Alamos, CERN, RAL)

First cavityFirst cavity

Be window to minimize thickness

The challenge:Thin windows + safety regulations


- STEP I

STEP II

STEP III

STEP IV

STEP V

STEP VI

MICE installation phases

2006

2007

2008


Muon acceleration

Previous accelerator scheme: LINAC + Recirculating Linear Accelerator (RLA)Very costly and rigid use.

Proposed solution:Fixed Field Alternating

Gradient (FFAG). a new a new type of accelerator with type of accelerator with B-field shaped as rB-field shaped as rk k

-->particles can be kept -->particles can be kept and accelerated over a and accelerated over a range of energies of range of energies of ~factor 3. ~factor 3.

New US Scheme

Japan Scheme


Muon acceleration: FFAG

Latest ideas in US have lead to the invention of a new type of FFAG (“non-scaling FFAG”) interesting for more than just Neutrino Factories (e.g. from SPL

to 20 GeV?) require a demonstration experiment (PRISM, electron prototype)

Perhaps US & Japanese concepts are merging to produce something better ??

Much progress in Japan with the development and demonstration of large acceptance FFAG accelerators


$$$$$ … COST … $$$$$$$$$$ … COST … $$$$$

USA, Europe, Japan have each their scheme for Nu-Fact. Only one has been costed, US 'study II' and estimated (2001) ~2B$.

The aim of the R&D is also to understand if solutions could reduce cost in half.

Neutrino Factory CAN be done…..but it is too expensive as is. Aim of R&D: ascertain challenges can be met + cut cost in half.

+ detector: MINOS * 10 = about 300 M€ or M$

28

Why we are optimistic:

We are working towards a “World Design Study” with an emphasis on cost reduction.

In the previous design ~ ¾ of the cost came from these 3 equally expensive sub-systems.

New design has similar performance to Study 2 performance and keeps both + and - ! (RF phase rotation)

S. Geer:

NUFACT 2004: cost can be reduced by at least 1/3 = proton driver + 1 B €

MAYBE the Neutrino Factory is not so far in the future after all….

$$$$$ … COST … $$$$$$$$$$ … COST … $$$$$


Beta beam Challenges

1. Intense production of ions, in particular + emitters (18Ne)

2. Clean acceleration: life time is much longer than muons but the decays produce activation in the rings)

3. Stacking in the storage ring


Layout very similar to planned EURISOL converter target aiming for 1015 fissions per s.

66He production by He production by 99Be(n,a)Be(n,a)

Converter technology: (J. Nolen, NPA 701 (2002) 312c)


Spallation of close-by target nuclides:18,19Ne from MgO and 34,35Ar in CaO

Production rate for 18Ne is 1x1012 s-1 (with 2.2 GeV 100 A proton beam, cross-

sections of some mb and a 1 m long oxide target of 10% theoretical density)

19Ne can be produced with one order of magnitude higher intensity but the half life

is 17 seconds!

A PULSED souce could be realized by ECR (P.Sortais Moriond 2003)

Production of Production of ++ emitters emitters


From dc ions to very short bunches

1 s

2.2 s

tB 1 s

t

B

PS

SPS

2.2 s

tB 1 s

PS

t

2 x 1.1 s to decay ring (4 bunches with few ns)

PS: 1s flat bottom with 8 (16) injections. Acceleration in ~1s to top PS energy

Target: dc production during 1 s.

60 GHz ECR: accumulation for 1/8 (1/16) s ejection of fully stripped ~20s pulse. 16 batches during 1s.

RCS: further bunching to ~100 ns Acceleration to ~300 MeV/u. 8 (16) repetitions over 1s.

SPS: injection of 8 (16) bunches from PS. Acceleration to decay ring energy and ejection of 4 + 4 bunches. Repetition time 8 s.

1 s 7 s

Post accelerator linac: acceleration to ~100 MeV/u. 8 (16) repetitions over 1s.

t


STACKING is necessary to ensure duty cycle less than 10-3

inject off energy(using e.g. dispersive section)


Summary

The construction of future neutrino facilities poses many stimulating challenges

Enthusiastic R&D is ongoing, and a lot has already been accomplished (despite all the difficulties related to lack of funding) -- much more is needed!

Many of these facilities offer other a large range of physics interests ranging from nuclear physics to rare muon decay and neutrinos -- AND… LHC upgrade…

The long term goal, LEPTONIC CP VIOLATION, makes the effort highly worthwhile

Documents

Rencontres du Viet-Nam 2004 Alain Blondel Challenges of future accelerator-based Neutrino Facilities Introduction Proton drivers Target and Collection