gdr neutrino, annecy 2007 beta-beam team1 beta-beams m. benedikt, a. fabich and m. lindroos, cern on...

GDR Neutrino, Annecy 2007

Beta-beam team 1

Beta-beams

M. Benedikt, A. Fabich and M. Lindroos, CERN

on behalf of the Beta-beam Study Group

http://cern.ch/beta-beam

BENE06/CARE06

http://cern.ch/beta-beam


Beta-beam team 2

Outline

• Beta-beam concept

• EURISOL DS scenario– Layout– Main issues on acceleration scheme– Physics reach

• Other scenarios– High-energy Beta-beams

• Study II• Summary


Beta-beam team 3

Beta-beam principle

Aim: production of (anti-)neutrino beams from the beta decay of radio-active ions circulating in a storage ring

– Similar concept to the neutrino factory, but parent particle is a beta-active isotope instead of a muon.

Beta-decay at rest– spectrum well known from electron spectrum– Reaction energy Q typically of a few MeV

• Accelerated parent ion to relativistic max– Boosted neutrino energy spectrum: E2Q– Forward focusing of neutrinos: 1/

• Pure electron (anti-)neutrino beam!– NB: Depending on +- or --decay we get a neutrino or anti-neutrino– Two (or more) different parent ions for neutrino and anti-neutrino beams

• Physics applications of a beta-beam– Primarily neutrino oscillation physics and CP-violation– Cross-sections of neutrino-nucleus interaction

=100


Beta-beam team 4

Guideline to -beam scenariosbased on radio-active ions

• Low-energy beta-beam: relativistic < 20– Physics case: neutrino scattering

• Medium energy beta-beam: 100– E.g. EURISOL DS– Today the only detailed study of a beta-beam accelerator complex

• High energy beta-beam: >350– Take advantage of increased interaction cross-section of neutrinos

• Monochromatic neutrino-beam– Take advantage of electron-capture process

• High-Q value beta-beam: 100

Accelerator physicists together with neutrino physicists defined the accelerator case of =100/100 to be studied first (EURISOL DS).


Beta-beam team 5

The EURISOL scenario

• Based on CERN boundaries• Ion choice: 6He and 18Ne

• Relativistic gamma=100/100– SPS allows maximum of 150 (6He) or 250 (18Ne)– Gamma choice optimized for physics reach

• Based on existing technology and machines– Ion production through ISOL technique– Post acceleration: ECR, linac– Rapid cycling synchrotron– Use of existing machines: PS and SPS

• Achieve an annual neutrino rate of either– 2.9*1018 anti-neutrinos from 6He– Or 1.1 1018 neutrinos from 18Ne

• Once we have thoroughly studied the EURISOL scenario, we can “easily” extrapolate to other cases. EURISOL study could serve as a reference.

EURISOL scenario


Beta-beam team 6

A new approach for the production

Beam cooling with ionisation losses – C. Rubbia, A Ferrari, Y. Kadi and V. Vlachoudis in NIM A, In press

“Many other applications in a number of different fieldsmay also take profit of intense beams of radioactive ions.”

7Li(d,p)8Li6Li(3He,n)8B

7Li6Li

Missed opportunities

See also: Development of FFAG accelerators and their applications for intense secondary particle production, Y. Mori, NIM A562(2006)591


Beta-beam team 7

Transverse cooling in paper by Carlo Rubbia et al.

“In these conditions, like in the similar case of the synchrotron radiation, the transverse emittance will converge to zero. In the case of ionisation cooling, a finite equilibrium emittance is due to the presence of the multiple Coulomb scattering.”


Beta-beam team 8

Longitudinal cooling in paper by Carlo Rubbia et al.

“In order to introduce a change in the dU/dE term — making it positive in order to achieve longitudinal cooling — the gas target may be located in a point of the lattice with a chromatic dispersion. The thickness of the foil must be wedge-shaped in order to introduce an appropriate energy loss change, proportionally to the displacement from the equilibrium orbit position.”

Number of turns1) Without wedge, dU/dE<0

2) Wedge with dU/dE=0, no longitudinal cooling

3) Wedge with dU/dE=0.0094

4) Electrons, cooling through synchrotron radiation


Beta-beam team 9

Inverse kinematics production and ionisation parameters in paper by Carlo Rubbia et al.

7Li(d,p)8Li6Li(3He,n)8B


Beta-beam team 10

Collection in paper by Carlo Rubbia et al.

“The technique of using very thin targets in order to produce secondary neutral beams has been in use for many years. Probably the best known and most successful source of radioactive beams is ISOLDE.”

Protons

+/- 8V500A

+/- 9V1000A

*


Beta-beam team 11

Reactions to study for our application

• 20Ne(p,t)18Ne– H.Backhausen et al, RCA,29(1981)1

• 16O(3He,n)18Ne– V.Tatischeff et al, PRC,68(2003)025804

• 6C(CO2,6He)18Ne?– K.I.Hahn et al, PRC,54(1996)1999

• 7Li(T,A)6He


Beta-beam team 12

Collection in a gas cell

• IGISOL technique (Ion Guide)

•Figure from Juha Aysto, Nucl.Phys. A693(2001)477

•At 200 Torr of 4He, 10% efficiency, space charge limit at 108 ions cm-3 (peak 1010 ions cm-3?), Private communication Ari Jokinen

BEAMGas cell

Extraction

Cool gas in


Beta-beam team 13

What about the intensities?

– Cross section similar or larger compared to those studied in detail in C. Rubbia et al.’s paper

– Heavier ions in the ring will require further beam dynamics study

– Space charge effects will set the limit for the IGISOL type device. With a 1000 cm3 gas cell, is 1011 ions s-1 realistic?

– Collection with foils as proposed by C. Rubia et al?


Beta-beam team 14

Intensity evolution during acceleration

Cycle optimized for neutrino rate towards the detector

• 30% of first 6He bunch injected are reaching decay ring• Overall only 50% (6He) and 80% (18Ne) reach decay ring

• Normalization– Single bunch intensity to maximum/bunch– Total intensity to total number accumulated in RCS

Bunch20th

15th

10th

5th1st

total


Beta-beam team 15

Dynamic vacuum

• Decay losses cause degradation of the vacuum due to desorption from the vacuum chamber

• The current study includes the PS, which does not have an optimized lattice for unstable ion transport and has no collimation system– The dynamic vacuum degrades to 3*10-8 Pa

in steady state (6He)

• An optimized lattice with collimation system would improve the situation by more than an order of magnitude.

1.00E+08

1.00E+09

1.00E+10

0 5 10 15 20 25 30 35

s [m]

6Li l

osse

s [/0

.1m

/6s-

cycl

e]

P. Spiller et al., GSI

C. Omet et al., GSI


Beta-beam team 16

Collimation and absorption

• Merging: – increases longitudinal emittance– Ions pushed outside longitudinal acceptance

momentum collimationin straight section

• Decay product– Daughter ion occurring continuously along

decay ring– To be avoided:

• magnet quenching: reduce particle deposition (average 10 W/m)

• Uncontrolled activation

– Arcs: Lattice optimized for absorber system OR open mid-plane dipoles

–

Straight section:Ion extraction et each end

s (m)

s (m)

Dep

osite

d P

ower

(W/m

)

x

Opt

ical

func

tions

(m) primary

collimatory

A. Chance et al., CEA Saclay


Beta-beam team 17

Decay ring magnet protection

• Absorbers checked (in beam pipe):• No absorber, Carbon, Iron, Tungsten

Theis C., et al.: "Interactive three dimensional visualization and creation of geometries for Monte Carlo

calculations", Nuclear Instruments and Methods in Physics Research A 562, pp. 827-829 (2006).


Beta-beam team 18

Longitudinal penetration in coil

No absorber Carbon Stainless Steel

Coil CoilAbs CoilAbs

Power deposited in dipole


Beta-beam team 19

Impedance, 340 steps!

Below 2.3 GHz, a total of 340 steps (170 absorbers) would add up to 0.5 H, which seems really high.

2 4 6 8 10

20

40

60

80

100

Im{Z}/

f/GHz

lowest cut-off (2.3 GHz)

Impedance of one step (diameter 6 to 10 cm or 10 to 6 cm):

L = 1.53 nH


Beta-beam team 20

Possible new solution

60 degrees

Cu or SS

Cu or SS sheets with 60 degrees opening on the sides

Top view, midplaneBetween

dipoles

In dipoles

beams

y [m

]


Beta-beam team 21

Intra Beam scattering, growth times

Results obtained with Mad-8

• 6He

• 18Ne


Beta-beam team 22

Objectives

• A High Intensity Neutrino Oscillation Facility in Europe – CDR for the three main options: Neutrino Factory,

Beta-beam and Super-beam– Focus on potential showstoppers– Preliminary costing to permit a fair comparison

before the end of 2011 taking into account the latest results from running oscillation experiments

– Total target for requested EU contribution: 4 Meuro• 1 MEuro each for SB, NF and BB WPs• 1 MEuro to be shared between Mgt, Phys and Detectors

WPs• 4 year project


Beta-beam team 23

Beta-beam WPs

• WP leader: Michael Benedikt, CERN• Deputy: Adrian Fabich, CERN • Objective:

– Coordination task: CERN leads the task, is responsible for the parameter list and for the overall coherence of the baseline scenario.

– Review task: The work will start with a review of the base line design for the new isotopes 8B and 8Li performed by CERN and CEA.

– Bunching task: The work at LPSC with the 60 GHz ECR source for bunching studies of 6He and 18Ne started within EURISOL DS will continue with the objective of reaching the high efficiencies needed for the beta-beam.. Furthermore, a study and first tests will be done at LPSC of necessary modification to bunch 8Li and 8B.

– Cross sections and collection device task: The cross section for the reaction channels of interest will be (re-)measured and a prototype for the collection device will be built and tested with stable beams at LLN.

– Superconducting magnets, magnet protection and collimation task: A pre-study of possible lay-out for superconducting dipoles for the beta-beam will be done at CERN and a baseline design will be identified. The work started on beam collimation and magnet protection in EURISOL DS will be adapated for 8Li and 8B at CERN and CEA

• Participating institutes: CERN, UCL, IN2P3 (LPSC), CEA• Additional partners: INFN (LNL), TRIUMF, RAS/IAP, Princeton, ANL


Beta-beam team 24

Management structure

STEERING COMMITTEESTEERING COMMITTEE1 representative of each Participant

+ Management Board and representatives of ECFA, ESGARD, BENE, IDS, EURISOL (all

ex-officio)1 meeting/year

MANAGEMENT BOARDMANAGEMENT BOARD

Project Leader + 2 Members

MANAGEMENT SUPPORT MANAGEMENT SUPPORT

COORDINATION BOARDCOORDINATION BOARDManagement Board+ Task Leaders

+ Coordinators of related EU activities (ex-officio)

2-3 Meetings/year

INTERNATIONAL ADVISORY INTERNATIONAL ADVISORY PANELPANEL

3 Members – 1 Meeting/year

ANNUAL PARTICIPANT ANNUAL PARTICIPANT MEETINGMEETING

1 Meeting/year

WP

Nufact

WP

BetaB

WP

MG

T

WP

Detec

WP

Phys

WP

SuperB


Beta-beam team 25

Annual participants meeting

• Annual meeting:– Monitoring of progress and coherence

of the study by SC and IAP members– Annual review of project deliverables

and milestones– Bringing the European Neutrino

oscillation community together• Physics community and machine

community


Beta-beam team 26

Summary

• Beta-beam accelerator complex is a very high technical challenge due to high ion intensities

• Activation• Space charge

– So far it looks technically feasible.• The physics reach for the EURISOL DS scenario is

competitive for >1O.– Usefulness depends on the short/mid-term findings by other

neutrino search facilities.• The physics made possible with the new production

concept proposed by Rubbia and Mori needs to be explored

• We need a study II– Plenty of new ideas!

Acknowledgment of the input given by M. Benedikt, A. Jansson, M. Mezzetto, E. Wildner, beta-beam task group and related EURISOL tasks

gdr neutrino, annecy 2007 beta-beam team1 beta-beams m. benedikt, a. fabich and m. lindroos, cern on...

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