BETA-BEAMSBETA-BEAMS363 days after

Piero Zucchelli - CERNPiero Zucchelli - CERN

M. MezzettoM. MezzettoD. CasperD. CasperM. LindroosM. LindroosU. KoesterU. KoesterS. HancockS. HancockB. AutinB. AutinM. BenediktM. BenediktH. HaserothH. HaserothM. GrieserM. GrieserA. JanssonA. JanssonS. RussenschuckS. RussenschuckF. WenanderF. Wenander

Physics Letters B 532 (3-4) (2002) pp. 166-172Physics Letters B 532 (3-4) (2002) pp. 166-172

GUIDELINESA. Neutrino beams from a different perspective

B. The “Beta-Beam” Concept

C. Experimental Scenario

D. Beta-beams and neutrino physics

E. Feasible? Cost-effective? Competitive?

Current talk, previous talks, tables, sources: http://cern.ch/Piero.Zucchelli/files/betabeam.A Website by this summer.

The focussing properties are given only by:- the divergence of the parent “beam” - the Lorentz transformations between different frames

PT= pT PL=( p + p cos)

from which, on average

1/ (it depends ONLY on parent speed!)EE0

and, in the forward direction,E2E0 (same rest-frame spectrum shape multiplied by 2)

Focussing Properties

parent

are produced by weak “decay” of a parent: ,K,nucleus. We assume the decay to be isotropic at rest and call E0 the rest frame energy of the neutrino.

LBL Scopemaximum neutrino flux for a given m2E/LE0/L.

The neutrino flux onto a “far” detector goes like 2/L2; Therefore (m2)2/E0

2.

At a given parent intensity, low energy decays in the CMS frame are the most efficient in achieving the “LBL requirement”, and independently of the factor.

But we want to observe neutrino interactions:N=

If we assume to be in the regime where E (>300 MeV for )N (m2)2 /E0

And acceleration enters into the game;

The “Quality Factor” of a “non-conventional” neutrino beam is therefore /E0

The BETA-BEAM1. Produce a Radioactive Ion with a short beta-decay lifetime

2. Accelerate the ion in a conventional way (PS) to “high” energy

3. Store the ion in a decay ring with straight sections.

4. It will decay. e (e) will be produced.

- SINGLE flavour - Known spectrum- Known intensity- Focussed- Low energy- “Better” Beam of e (e)

The “quality factor” QF=/E0 is bigger than in a conventional neutrino

factory. In addition, ion production and collection is easier. Then, 500000X more time to accelerate.

Muons:~500E0~34 MeVQF~15

6He Beta-:~150E0~1.9 MeVQF~7918Ne Beta+:~250E0~1.86 MeVQF~135

Possible - emitters (e)

Isotope Z A A/Z T1/2 Q (gs>gs) Q eff. E av. E av. <E_LAB> ( MeV)

s MeV MeV MeV MeV (@ 450 GeV/p)

6He 2 6 3.0 0.807 3.5 3.5 1.57 1.94 582

8He 2 8 4.0 0.119 10.7 9.1 4.35 4.80 1079

8Li 3 8 2.7 0.838 16.0 13.0 6.24 6.72 2268

9Li 3 9 3.0 0.178 13.6 11.9 5.73 6.20 1860

11Be 4 11 2.8 13.81 11.5 9.8 4.65 5.11 1671

15C 6 15 2.5 2.449 9.8 6.4 2.87 3.55 1279

16C 6 16 2.7 0.747 8.0 4.5 2.05 2.46 830

16N 7 16 2.3 7.13 10.4 5.9 4.59 1.33 525

17N 7 17 2.4 4.173 8.7 3.8 1.71 2.10 779

18N 7 18 2.6 0.624 13.9 8.0 5.33 2.67 933

23Ne 10 23 2.3 37.24 4.4 4.2 1.90 2.31 904

25Ne 10 25 2.5 0.602 7.3 6.9 3.18 3.73 1344

25Na 11 25 2.3 59.1 3.8 3.4 1.51 1.90 750

26Na 11 26 2.4 1.072 9.3 7.2 3.34 3.81 1450

Possible + emitters (e)

Isotope Z A A/Z T1/2 Q (gs>gs) Q eff. E av. E av. <E_LAB> (MeV)

s MeV MeV MeV MeV (@450 GeV/p)

8B 5 8 1.6 0.77 17.0 13.9 6.55 7.37 4145

10C 6 10 1.7 19.3 2.6 1.9 0.81 1.08 585

14O 8 14 1.8 70.6 4.1 1.8 0.78 1.05 538

15O 8 15 1.9 122.2 1.7 1.7 0.74 1.00 479

18Ne 10 18 1.8 1.67 3.4 3.4 1.50 1.86 930

19Ne 10 19 1.9 17.34 2.2 2.2 0.96 1.25 594

21Na 11 21 1.9 22.49 2.5 2.5 1.10 1.41 662

33Ar 18 33 1.8 0.173 10.6 8.2 3.97 4.19 2058

34Ar 18 34 1.9 0.845 5.0 5.0 2.29 2.67 1270

35Ar 18 35 1.9 1.775 4.9 4.9 2.27 2.65 1227

37K 19 37 1.9 1.226 5.1 5.1 2.35 2.72 1259

80Rb 37 80 2.2 34 4.7 4.5 2.04 2.48 1031

Anti-Neutrino SourceConsider 6He++6Li+++ e e-

E03.5078 MeV T/2 0.8067 s

1. The ion is spinless, and therefore decays at rest are isotropic.

2. It can be produced at high rates, I.e.5E13 6He/s

3. The neutrino spectrum is known on the basis of the electron spectrum.

DATA and theory:<Ekine>=1.578 MeV<E>=1.937 MeVRMS/<E>=37%

B.M. Rustand and S.L. Ruby, Phys.Rev. 97 (1955) 991B.W. Ridley Nucl.Phys. 25 (1961) 483

Neutrino Source

Possible neutrino emitter candidate:18Ne

The same technology used in the production of 6He is limitedin the 18Ne case to 1012 ions/s.Despite it is very reasonable to assume that a dedicated R&D will increase this figure, this intensity is used as “today” reference.

Issues: MgO less refractory,heat dissipation

The Acceleration principle

ISOL Target and ECR

Linac Cyclotron Storage Ring

PS SPS

2500 m

R=300 m

Decay ring/Buncher

Bunch rotation is the crucial issue for atmospheric background control!

Studies are made on EXISTING CERNmachines. Why? Much more detailedknowledge exists, the best way to identifypossible problems and limitations.

Bunched?

2500 m

R=300 m

The interactions time structurein the detector is identical to thetime structure of the parents in the decay ring in a given position.

The beta decay position does not matter, since the parents have the same speed of the neutrinos

The far detector duty cycle is bunch length / ring length

A

B

Inte

ract

ions

time

Ion

inte

nsity

time

The Decay Ring

100kW decay losses into the decay ringOne bunch of 10 ns length

From the physics point of view,the bigger the ring is, the better.

straight section relative length fixed to 2500 m (~SPS diameter).The ring is essentially flat below ground (10 mrad).

5T curvatureradius 300 mstraight 2500 mfield 600X3100 m2

B x radius 1500 TmB field 5 T radius of curvature 300 mstraight section length 2500 mring length 6885 mRelative straight section length 36%

A Neutrino Physics ScenarioIt is reasonable to assume that - in the next years -savings issues will dominate the scenario in EU HEP.

A. Imagine a neutrino detector that could do Physics independently of the neutrino factory.

B. Imagine to build it, to run it, and to explore non-accelerator physics.

C. Imagine that, as soon as the SPL will be ready (~2015?), you make a superbeam shooting muon neutrinos onto it. If this will expand the physics reach, and you’re competitive with the other world programs, you’re ready to do it (known technology).

D. Imagine that you have PREPARRED and STUDIED an option to shoot electron neutrinos onto the same detector. If thenext neutrino physics will demand it, you’re ready to do it.

A Dream?

A. the ~600 Kton UNO detector.

B. Supernovae, Solar, Atmospheric, Proton Decay:12,m12,23,m23.

C. Frejus site and SPL Super-Beam: possibly 13

D. Frejus site and SPS Beta-Beam: possibly 13 , possibly CP (2) and T

Is this physics program less wide than a muon-based neutrino factory program?

The objectives are wider, the discovery potential is smaller. But,for example, we will see that the information on , if within reach, is even more comprehensive than a muon-based nufactory.

SuperBeam Sinergy

The proton requirements of the Beta-Beam are part of the ISOLDE@SPL (100uA for 1s every 2-5 s).

The ISOLDE@SPL plans 100 uA protons overall.

The Superbeam uses 2mA from the SPL.

Therefore:The BetaBeam affects the SuperBeam intensity by 3% at most.

Why Cherenkov?The detector needsto be very massive, and capable todistinguish electrons from muons

Same requirementof the SuperBeam!

You don’t need the charge identification...

...Therefore you don’t need a magnetic detector!

The Far Detector ObservablesThe relative neutrino flux for a spinless* parents is ONLYfunction of and L, not even of the parent itself.

Distance (km) Relative Flux (nu/m2)1 7.1109E-03

12.5 4.5834E-0550 2.8647E-06

100 7.1618E-07130 4.2378E-07

22

11)cos(

)cos(1

)cos()cos(

2

)cos(1

mL

l

l

lr

rP

(* as it is for 6He and 18Ne)

beam-related backgrounds due to Lithium/Fluorine interactions at the end of the straightsections

The Far Detector Background

GEANT3 simulation,

3E6 proton interactionsonto a Fe dump,

tracking down to 10 MeV

100 mradoff-axis and 130 km distance.DIF and DAR (K+) contributions

<10-4 background @ =150

antineutrinos interactions on Oxygen are typicallypenalized by a factor ~ 6.

Cross Sections

T.K Gaisser and J.S. O’Connel, P.R.D34,3 (1986) 822.

However: Free protons of H2Oshould also be included

The Signal maximization...

The signal coming from appearance interactions after oscillation @ 130 kmand 440 kt-year fiducial mass in the hypothesis (13=/2,m13=2.4E-3 eV2). The machine duty-cycle is assumed to remain constant.

table

0

5000

10000

15000

20000

95 115 135 155 175

Gamma

Osc

illat

ed a

nd

In

tera

cted

/Yea

r

…and the interaction background...

NC interactions potentially produce ++ decays (almost at rest)and the + is misidentified as a muon.

Asymmetries with Superbeams start to appear (the e/0 separation becomes /)

Kinematical cuts are possible, still delicate and MC dependent.

Another strategy consists in having the pions below Cherenkov threshold (see later).

InteractionBackground

...and the Atmospheric “background”

The atmospheric neutrino background has to be reduced mainlyby “timing” on the 6He bunches (protons for the SuperBeam).

The shortness of the ion bunches is therefore mandatory(10 ns for a ~SPS ring length).

However, the directionality of the antineutrinos can be usedto further suppress this background by a factor ~4-6X dependent on gamma.

AtmosphericBackground

Anu

e S

umm

ary

Num

bers

Quantity Value Unit CommentsSPS Cycle time 5 sProduced 6He 2.0E+13 per cyclemachine livetime 1.0E+07 s/year

Produced 6He/year 4.0E+19

Transfer efficiency 25%

6He injected into storage ring per year 1.0E+19

Straight section relative length 36%

Gamma 150potential 6He decays 3.6E+18 in one straight section

Interaction rate/6He/kton 2.3E-17 130 km, G=150Ring length 6885 mnumber of bunches 1 Single Bunch stackingBunch intensity 5.0E+12 6HeStorage ring total intensity 7.8E+13 6He 1/(1-exp(-8/120))Bunch spacing 22950 nsBunch length 10 nsstorage ring occupation 4.4E-04 bunch length/ring lengthUseful 6He decays 3.63E+18 cutoff in storage timeBetabeam anue Interactions 85 events/kton/yearBetabeam anumu Interactions 84 events/kton/yearOscillation interactions (1.0,2.4E-3) 31 events/kton/yearSignal emission time 4357 sAtmospheric Background 50 event/kton/yearyear 3.2E+07 s Detector fiducial mass 440 ktonAtmospheric Background 0.8 events/year kinematical/angular cuts (4X)Beam Background 1.4 events/yearAnue interactions 37247 events/yearOscillation signal 13756 events/yearNoise/Oscillation Signal 1.55E-04

The Nue case

Neon production Intensity is lower, HOWEVER:

1. 18Ne has charge 10 and mass 18.

2. For the previous reason, SPS can accelerate the ion up to=250 (250 GeV/nucleon) WITH THE SAME MAGNETIC FIELDused for 6He and =150.

<E>=0.93 GeV !!!

3. For the same reasons explained for the antineutrino case, the potential oscillation signal improves despite the fact <E>/L=7E-3 GeV/km

Nue

Sum

mar

y N

umbe

rsQuantity Value Unit CommentsSPS Cycle time 5.0 sProduced 18Ne 8.0E+11 per cyclemachine livetime 1.0E+07 s/yearProduced 18Ne/year 1.6E+18Transfer efficiency 38%18Ne injected into storage ring per year 6.0E+17Straight section relative length 36%Gamma 250potential Ne18 decays 2.2E+17 in one straight sectionInteraction rate/18Ne/kton 2.0E-16 130 km, G=75Ring length 6885 mnumber of bunches 1 Single Bunch stackingBunch intensity 3.0E+11 18NeStorage ring total intensity 2.4E+13 18Ne 1/(1-exp(-8/120))Bunch spacing 22950 nsBunch length 10 nsstorage ring occupation 4.4E-04 bunch length/ring lengthUseful 18Ne decays 2.2E+17 cutoff in storage timeBetabeam QE nue Interactions 43.09 events/kton/yearBetabeam QE numu Interactions 42.44 events/kton/yearOscillation interactions (1.0,2.4E-3) 9.25 events/kton/yearSignal emission time 4357 sAtmospheric Background 50 event/kton/yearyear 3.2E+07 s Detector fiducial mass 440 ktonAtmospheric Background 0.8 events/yearBeam Background 0.4 events/yearNue interactions 18958 events/yearOscillation signal 4071 events/yearNoise/Oscillation Signal 2.87E-04

The Super-BetaSuper-Beta Beams (SPL-BB)

(Old) Super-Beam numu: 9,800 QE/Year @ 260 MeV @ 130 km

Beta-Beam anue: 37,250 QE/Year @ 580 MeV @ 130 km

(Old) Super-Beam anumu: 2050 QE/Year @ 230 MeV @ 130 km

Beta-Beam nue: 18,950 QE/Year @ 930 MeV @ 130 km

Obviously: the SuperBeam lower energy is “better”. Still,the oscillation probability of the Beta-Beams are 37% (anue)and 15% (nue) respectively.The SuperBeam has more beam-related background, but is much simpler to do.Beta-beam detector backgrounds to be studied.

ONE DETECTOR, ONE DISTANCE, 2X2 BEAMS!

A CP or a T search?

J. Sato, hep-ph 0006127

In the T search, ambiguities are resolved!The tunability of the beta-beam allows additional choiceof the phase cot (m2

13 L / 4E)

CP Asymmetry

T Asymmetry

General ConsiderationsA.13 is just the starting step for super&beta-beams.

B. CP violation at low energy is almost exempt from matter effect, therefore already particularly attractive (nue beta-beam, anue beta-beam).

C. Who else can do T violation without magnetic field and electron charge identification? (nue beta-beam, numu super-beam).

D. CPT test by anue beta-beam, numu super-beam is the ultimate validation of the 3-family mixing model and of the CP and T measurements.

E. If LSND is confirmed, 6 mixing angles and 3 CP violation phases are waiting for us! The smallness of the LSND mixing parameter implies high purity beams, the missing unitarity constraints will demand sources with different flavours.

H. Minakata, H. Nunokawa hep-ph0009091.

CPT Asymmetry

One simple Optimization

At the same time, it maximizes the overlap with the CP-oddterm (at CERN-Frejusdistance)

Background should not generate a Cherenkov signal!

BetaBeam “downgrading”Quantity Value Unit CommentsSPS Cycle time 2.0 sproduced 18Ne 8.0E+11 per cyclemachine livetime 1.0E+07 s/year

Produced 18Ne/year 4.0E+18

Transfer efficiency 38%

18Ne injected into storage ring per year 1.5E+18

Straight section relative length 36%

Gamma 75potential Ne18 decays 5.4E+17 in one straight section

Interaction rate/18Ne/kton 8.3E-18 130 km, G=75Ring length 6885 mnumber of bunches 1 Single Bunch stackingBunch intensity 3.0E+11 18NeStorage ring total intensity 1.8E+13 18Ne 1/(1-exp(-8/120))Bunch spacing 22950 nsBunch length 10 nsstorage ring occupation 4.4E-04 bunch length/ring lengthUseful 18Ne decays 5.45E+17 cutoff in storage timeBetabeam QE nue Interactions 4.52 events/kton/yearBetabeam QE numu Interactions 3.79 events/kton/yearOscillation interactions (1.0,2.4E-3) 3.06 events/kton/yearSignal emission time 4357 sAtmospheric Background 50 event/kton/yearyear 3.2E+07 s Detector fiducial mass 440 ktonAtmospheric Background 0.8 events/yearBeam Background 0.1 events/yearNue interactions 1989 events/yearOscillation signal 1347 events/yearNoise/Oscillation Signal 6.64E-04

=75

, F

lux

Dro

p, B

ackg

roun

d D

rop

11X Flux Drop!!!

General ConsiderationsThe neutrino factory golden-measurement is the CP violation. Super-Beam+Beta-Beam are competitive in various ways, including T violation!

= 90 deg99%C.L. Curves

(M. Mezzetto, NNN02)

Nu2002 comparison chart

F. Dydak

~10-4

~1

YesYes

Let’s Fill the BB column!

0.2-2 GeV

Comment on BB cost estimates

Educated guess on possible costs USD/CHF 1.60UNO 960 MCHFSUPERBEAM LINE 100 MCHFSPL 300 MCHFPS UPGR. 100 MCHFSOURCE (EURISOL), STORAGE RING 100 MCHFSPS 5 MCHFDECAY RING CIVIL ENG. 400 MCHFDECAY RING OPTICS 100 MCHF

TOTAL (MCHF) 2065 MCHFTOTAL (MUSD) 1291 MUSD

INCREMENTAL COST (MCHF) 705 MCHFINCREMENTAL COST (MUSD) 441 MUSD

My Last Words

1. the Beta-Beams are possible!

3. Natural part of a program that starts with a non-accelerator Water Cherenkov phase and a SuperBeam phase. The program covers supernovae detection, proton decay, atmospheric neutrinos, solar neutrinos, 13 search, CP asymmetry, T asymmetry, CPT asymmetry.

4. Scaled technology approach based on existing accelerator technology

2. Unique, unprecedented high intensity high purity ee beams

“Se son rose, fioriranno”. “If they're roses, they will blossom”

“Si tiene barbas, San Antón, si no la Purísima Concepción”