# Presentation: 188346

## BETA-BEAMS

- Idea, Progress, Feasibility

- Piero Zucchelli
- CERN

- CERN-EP/2001-056
- HEPEX-0107006
- (Subm. To PLB)
- http://cern.ch/Piero.Zucchelli/files/betabeam/nnn02.ppt

- 6He

## GUIDELINES

**1. Neutrino beams from a different perspective**

**2. The “Beta-Beam” Concept**

**5. Neutrino physics impact**

**3. Insight on the radioactive ions production**

**4. Acceleration schemes**

- Previous talks, tables and some sources:
- http://cern.ch/Piero.Zucchelli/files/betabeam

## Focussing Properties

**- the divergence of the parent “beam” **
**- the Lorentz transformations between different frames**
**	****	****P****T****= ****p****T**** **
**	****	****P****L****=********( ****p**** + ****p**** ******** cos************)**
**from which, on average (if spinless)**
******1/******** ****	****	****(it depends ONLY on parent speed!)**
**E********E****0****	****	**** ****E****0**** =daughter particle energy  when parent is at rest**
**where. In the forward direction,**
**E********2********E****0**** (I.e. same rest-frame spectrum shape multiplied by 2********)**

****

## LBL Requirement

**maximum neutrino flux for a given ********m****2********E/L********E****0****/L.**

- The neutrino flux  onto a “far” detector goes like 2/L2; Therefore
-  			  (m2)2/E02.
- 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.
- We want to observe neutrino _interactions_, therefore:
- 	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” QF of a
- “non-conventional”  neutrino beam is   /E0

## The BETA-BEAM

- 1. 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 storage ring with straight sections.
- 4. It will decay. e (e) will be produced.

- The “quality factor” QF=/E0 is bigger than in a conventional neutrino
- factory. In addition, production & acceleration (500000 more time) are simpler.

- Muons:
- ~500
- E0~34 MeV
- QF~15

- 6He Beta-:
- ~150
- E0~1.9 MeV
- QF~79

- 18Ne Beta+:
- ~250
- E0~1.85 MeV
- QF~135

## The Anti-Neutrino Source

- Consider 6He++6Li+++  e e-

- Q=3.5078 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

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

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

- 3.5 MeV

**DATA and theory:**
**<Ekine>=1.578 MeV**
**<E********>=1.937 MeV**
**RMS/<E********>=37%**

## The Anti-Neutrino Source

- High 6He production rates
- are possible in the
- “Second Generation
- Radioactive Nuclear
- Beam Facility at CERN”
- based on the SPL.
- (CERN/EP 2000-149)

- CONVENTIONAL
- TODAY
- TECHNOLOGY
- ASSUMPTIONS

- Physics reference number:
- 5X1013 6He/s every 8s

## The Neutrino Source

- Possible neutrino emitter candidate:18Ne (spinless!)
- The same technology used in the production of  6He is limited
- in the 18Ne case to ~1012 ions/s.
- Despite it is 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

- Physics reference number:
- 1012 18Ne/s every 8s

## Possible - emitters

**U. Köster, EP-ISOLDE**

## Possible + emitters

**U. Köster, EP-ISOLDE**

## “Easy” ISOL elements  

**Elements compatible with a “cold-body” ECR ion source**

**U. Köster, EP-ISOLDE**

## 6He production by 9Be(n,)

**9****Be(n,********)****6****He reaction favorable:**
**Threshold: 0.6 MeV****	**
**Peak cross-section 105 mb**
**Good overlap with evaporation part of spallation neutron spectrum: n(E)********E*exp(-E/E****e****)**
**E****e****: 2.06 MeV for 2 GeV p on Pb**
**BeO very refractory**

****** ****9****Be(n,********)****6****He**
**EXFOR data**

**6****Li(n,p)****6****He reaction less interesting:**
**Threshold: 2.7 MeV**
**Peak cross-section 35 mb**
**Li compounds rather volatile**

**U. Köster, EP-ISOLDE**

## 6He production by 9Be(n,)

**Layout very similar to planned EURISOL converter target aiming for 10****15**** fissions per s.**

**Converter technology: ***J. Nolen et al., NPA, RNB-5, in press***.**

**U. Köster, EP-ISOLDE**

## 6He production by 9Be(n,)

- Converter scenario:
- 60 cm long liquid Pb or water-cooled W converter
- 100 A of 2.2 GeV proton beam
- about 20 to 40 neutrons produced per incident proton (dependent on converter diameter, see: ***G.S. Bauer, NIM A463 (2001) 505***)
- thereof about half in suitable angle and energy range
- BeO fiber target in 5 cm thick concentric cylinder around converter
- packed to 10% theoretical density (very conservative)
- production rate: roughly 5E13 per s (requires MC calculation!)

**U. Köster, EP-ISOLDE**

## Oxide fiber targets

- Oxide fiber targets:
- high open porosity   fast release

**U. Köster, EP-ISOLDE**

## The Acceleration EXAMPLE

- ISOL
- target

- ECR
- source

- Linac
- 20 MeV/u

- Accumulator
- >~300 MeV/u

- PS

- SPS
- 450 GeV/p

- Physics reference numbers:
- 65%Transmittance into the decay ring
- =150 for 6He
- Acceleration cycle into the storage ring: 8s

- Decay ring and
- bunch rotation

- Bunch rotation is the crucial issue for atmospheric background control

**M. Lindroos**

## Parameters

- All emittances are 95% (4 sigma) in units of Pi mm mrad  Total cycle time 8 seconds

**M. Lindroos**

## PS

- Acceleration of ions for injection into SPS
- 5-10 GeV/u
- Challenges:
- High tune shift (0.3-0.5) at injection
- _Losses during acceleration are critical in CERN PS_
- Transport and collimation of two ion species

**M. Lindroos**

## The Storage Ring

- Physics reference numbers:
- 36% (X2)  useful decays
- 100kW into the storage ring
- Bunch rotation: 15 ns length

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

**M. Lindroos**

## Bunch stacking and storage ring

- Bunch Stacking Scheme:
- Particles in single bunch from SPS
- Bunch merging with slip-stacking
- Fast kickers in decay ring

- Storage ring requirements
- High intensity single bunch of 15 ns length
- Two RF systems for beam merging and bunch rotation
- Challenges
- High Energy electron cooling system?
- Beam loading in RF cavities
- Transport and collimation of two ion species

**M. Lindroos**

- SPS _DATA_

## DR RF manipulation

- RF voltage

- Time

- Merging

- Rotation

- Merging

- Rotation

- 8 s

- RF1 (h= #)

- RF2 (h= 2 * #)

**M. Lindroos**

## The Storage Ring

**Is a 5T bending feasible at all in a “hot” environment?**

- This problem is not new to LHC (3E14 protons at 7 TeV)

- Handling the proton beams much above the quench limit / Jeanneret, J B ;
-     Pres. at: 10th Workshop on LEP-SPS Performance,
- Chamonix, France, 17 - 21 Jan 2000 CERN, Geneva, Feb 2000. [CERN-SL-2000-007-DI] - pp.162-168

## The Storage Ring

- Handling the proton beams much above the quench limit / Jeanneret, J B ;
-     Pres. at: 10th Workshop on LEP-SPS Performance,
- Chamonix, France, 17 - 21 Jan 2000 CERN, Geneva, Feb 2000. [CERN-SL-2000-007-DI] - pp.162-168

- The losses in the
- storage ring
- are BELOW the
- “Allowed steady losses”
- for the (unshielded)
- 7 Tesla LHC magnets.

## A Neutrino Physics Scenario

- It is reasonable to assume that - in the next years -
- savings issues will dominate the scenario in EURO - HEP.
- A. *Imagine* a neutrino detector that could do **P**hysics
- independently of a beam.
- B. *Imagine* to build it, to run it, and to explore relevant
- non-accelerator **P**hysics.
- C. *Imagine* that, as soon as the SPL will be ready (~2010), you get 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 the
- next neutrino physics will demand it, you’re ready to do it.

## A Neutrino Physics Scenario

- Is this _PROGRAM_ conceivable?
- A. the ~600 Kton UNO detector.
- B. Supernovae, Solar, Atmospheric neutrinos. Proton Decay:
- 12,m12,23,m23.
- C. Frejus site and SPL Super-Beam: possibly 13
- D. Frejus site, SPL Super-Beam and SPS Beta-Beam:
- possibly 13  phase II, CP, T , CPT, near detector program.

- Physics reference numbers:
- L=130 km
- Fiducial Mass=440 Kton, H2O

## SuperBeam Sinergy

- The proton requirements of the SuperBeam are 1/8 of the
- ISOLDE@SPL (100uA for 1s every 8 s).
- The ISOLDE@SPL plans 100 A protons overall.
- The Superbeam uses 2mA from the SPL.
- Therefore:
- _The BetaBeam reduces the SuperBeam intensity by 0.6%._

## Why Cherenkov?

- You “just” need
- electron and muon
- identification.
- Same requirement
- of the SuperBeam.
_**You don’t need **_
_**the charge **_
_**identification.**_
_**You don’t need **_
_**a magnetized**_
_**detector.**_

## The Far Detector Observables

- D. Casper pointed out the analytical expression of the
- relative neutrino flux for _**spinless**_ parents :

- (Verified by Toy MC)

## The Far Detector Background

- due to Lithium
- interactions at the
- end of the straight
- sections

- GEANT3 simulation,
- 3E6 proton
- interactions
- onto a Fe dump,
- tracking down to 10 MeV
- 100 mrad
- off-axis and
- 130 km distance.
- DIF and DAR
- (K+) contributions

- ~10-4 background

## Cross Sections

- Oxygen are typically
- penalized by a factor ~ 5.

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

- Free protons of H2O
- are also included

## The Far Detector Interactions

- Simple approach:
- maximization of
- oscillation signal
- which corresponds
- to the hardest
- possible spectrum

## The Signal maximization

- The signal coming from appearance anti  interactions in the
- hypothesis (sin2e=1.0,m13=2.4E-3 eV2). The SPS duty-cycle
- is assumed to remain constant to 8s.

- table

## The Signal Spectrum

- The beam

-  interactions

- Oscillated
- 
- interactions

- 37% of nue oscillate
- and interact as 

## Anue Summary Numbers

## The e case

- 18Ne Intensity feasible today is 20lower than 6He , HOWEVER:
- 1. 18Ne, like all beta+ emitters, has a A/Z value smaller than
- for 6He and beta- emitters.
- 2. Therefore SPS can accelerate the ion up to
- =250 (250 GeV/nucleon) WITH THE SAME MAGNETIC FIELD
- used for 6He and =150.
- <E>=930 MeV !!!
- 3. For the same reasons explained for the antineutrino case, the
- appearance search improves at large gamma despite the fact
- <E>/L=7E-3 GeV/km
- 4. The quality factor /E0  gives a bonus of 1.7and the better cross-sections
- another factor ~So, the initial gap of 20is “JUST” a factor 2

## Nue Summary Numbers

## Comment on the “stacking option”

- Stacked bunch intensity:

- Vacuum lifetime
- and debunching
- reduce the effective
- intensity of the beam.
- Less problematic for 6He

- 6He

- 18Ne

- Time (s)

- Ion intensity in the ring

## Super-Beta-UNOinteraction rates

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

- Beta-Beam anue: **30,300 QE/Year @ 580 MeV @ 130 km****	**

- Super-Beam anumu: **2050 QE/Year @ 230 MeV @ 130 km****	**

- Beta-Beam nue: **15450 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 22% (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!

## General Considerations

- A.13 is just the starting step for super&beta-beams.
- B. CP violation at low energy is almost exempt from matter effect, therefore 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). See Mauro’s talk.
- CPT test to measure the sign of m2: anue beta-beam, numu super-beam.
- D. 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.

- T Test:

- CPT Test:sign

## The  “Feasibility” road

- A. Deeper  studies “UNO-like” based on full simulation of the
- “detector” backgrounds, beam optimization and physics analysis.
- B. Deeper study of a complete realistic acceleration scheme

## CONCLUSIONS

-  “If they're roses, they will blossom”

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

- e