Transcript Document 7559279

b
The Beta-beam
http://cern.ch/beta-beam
Mats Lindroos
on behalf of
The beta-beam study group
Benasque
Collaborators
• The beta-beam study group:
–
–
–
–
–
–
–
–
–
–
–
b
CEA, France: Jacques Bouchez, Saclay, Paris Olivier Napoly, Saclay, Paris
Jacques Payet, Saclay, Paris
CERN, Switzerland: Michael Benedikt, AB Peter Butler, EP Roland Garoby,
AB Steven Hancock, AB Ulli Koester, EP Mats Lindroos, AB Matteo
Magistris, TIS Thomas Nilsson, EP Fredrik Wenander, AB
Geneva University, Switzerland: Alain Blondel Simone Gilardoni
GSI, Germany: Oliver Boine-Frankenheim B. Franzke R. Hollinger Markus
Steck Peter Spiller Helmuth Weick
IFIC, Valencia: Jordi Burguet, Juan-Jose Gomez-Cadenas, Pilar Hernandez,
Jose Bernabeu
IN2P3, France: Bernard Laune, Orsay, Paris Alex Mueller, Orsay, Paris
Pascal Sortais, Grenoble Antonio Villari, GANIL, CAEN Cristina Volpe, Orsay,
Paris
INFN, Italy: Alberto Facco, Legnaro Mauro Mezzetto, Padua Vittorio
Palladino, Napoli Andrea Pisent, Legnaro Piero Zucchelli, Sezione di Ferrara
Louvain-la-neuve, Belgium: Thierry Delbar Guido Ryckewaert
UK: Marielle Chartier, Liverpool university Chris Prior, RAL and Oxford
university
Uppsala university, The Svedberg laboratory, Sweden: Dag Reistad
Associate: Rick Baartman, TRIUMF, Vancouver, Canada Andreas Jansson,
Fermi lab, USA, Mike Zisman, LBL, USA
Benasque
The beta-beam
b
• Idea by Piero Zucchelli
– A novel concept for a neutrino factory: the
beta-beam, Phys. Let. B, 532 (2002) 166-172
• The CERN base line scenario
– Avoid anything that requires a “technology
jump” which would cost time and money (and be
risky)
– Make use of a maximum of the existing
infrastructure
– If possible find an “existing” detector site
Benasque
CERN: b-beam baseline scenario
 ,
Nuclear
Physics
b
SPL
Decay ring
Brho = 1500 Tm
B=5T
Decay
ISOL target
& Ion source
Ring
SPS
6
2
ECR
Benasque
He 36Li e 
Average Ecms  1.937 MeV
Cyclotrons,
linac or FFAG
Rapid
cycling
synchrotron
Lss = 2500 m
18
10
Ne189Fe e 
Average Ecms  1.86 MeV
PS
 ,
Target values for the decay ring
6Helium2+
–
–
–
–
In Decay ring: 1.0x1014 ions
Energy:
139 GeV/u
Rel. gamma: 150
Rigidity:
1500 Tm
b
18Neon10+
–
–
–
–
(single target)
In decay ring: 4.5x1012 ions
Energy:
55 GeV/u
Rel. gamma: 60
Rigidity:
335 Tm
• The neutrino beam at the experiment will have the
“time stamp” of the circulating beam in the decay ring.
• The beam has to be concentrated to as few and as short
bunches as possible to aim for a duty factor of 10-4
Benasque
SPL, ISOL and ECR
SPL
ISOL
Target
+ ECR
Linac,
cyclotron
or FFAG
b
Rapid
cycling
synchrotron
PS
SPS
Decay
ring
Objective:
• Production, ionization and pre-bunching of ions
Challenges:
• Production of ions with realistic driver beam
current
– Target deterioration
• Accumulation, ionization and bunching of high
currents at very low energies
Benasque
ISOL production
b
+
spallation
201
1 GeV p
Fr
fragmentation
+
238
11
U
Li
+
X
fission
n
p
+
143
Benasque
Cs
+
Y
6He
production by 9Be(n,a)
Converter technology:
(J. Nolen, NPA 701 (2002)
312c)
Courtesy of Will Talbert,
Mahlon Wilson (Los Alamaos)
and Dave Ross (TRIUMF)
Layout very similar to planned EURISOL converter target
aiming for 1015 fissions per s.
Benasque
b
Mercury jet converter
b
H.Ravn, U.Koester, J.Lettry,
S.Gardoni, A.Fabich
Benasque
Production of b+ emitters
b
• 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 mA 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!
Benasque
60-90 GHz « ECR Duoplasmatron » for pre-bunching of gaseous RIB
2.0 – 3.0 T pulsed coils
or SC coils
Very high density
magnetized plasma
ne ~ 1014 cm-3
Target
Very small plasma
chamber  ~ 20 mm / L ~ 5 cm
Arbitrary distance
if gas
Rapid pulsed valve
 1-3 mm
100 KV
extraction
UHF window
or « glass » chamber (?)
Pascal Sortais et al.
LPSC-Grenoble
60-90 GHz / 10-100 KW
10 –200 µs /  = 6-3 mm
optical axial coupling
20 – 100 µs
20 – 200 mA
12
10 to 1013 ions per bunch
with high efficiency
Moriond meeting:
Benasque
b
optical radial coupling
(if gas only)
Low-energy stage
SPL
ISOL
Target
+ ECR
Linac,
cyclotron
or FFAG
b
Rapid
cycling
synchrotron
PS
SPS
Decay
ring
Objective:
• Fast acceleration of ions and
injection
• Acceleration of 16 batches to 100
MeV/u
Benasque
b
Rapid Cycling Synchrotron
SPL
ISOL
Target
+ ECR
Linac,
cyclotron
or FFAG
Rapid
cycling
synchrotron
PS
SPS
Decay
ring
Objective:
• Accumulation, bunching (h=1), acceleration and
injection into PS
Challenges:
• High radioactive activation of ring
• Efficiency and maximum acceptable time for
injection process
– Charge exchange injection
– Multiturn injection
• Electron cooling or transverse feedback system to
counteract beam blow-up?
Benasque
b
PS
SPL
ISOL
Target
+ ECR
Linac,
cyclotron
or FFAG
Fast
cycling
synchrotron
PS
SPS
Decay
ring
• Accumulation of 16 bunches at 300 MeV/u
• Acceleration to g=9.2, merging to 8
bunches and injection into the SPS
• Question marks:
– High radioactive activation of ring
– Space charge bottleneck at SPS injection will
require a transverse emittance blow-up
Benasque
Overview: Accumulation
• Sequential filling of 16 buckets in the PS
from the storage ring
Benasque
b
SPS
SPL
b
ISOL
Target
+ ECR
Linac,
cyclotron
or FFAG
Fast
cycling
synchrotron
PS
SPS
Decay
ring
Objective:
• Acceleration of 8 bunches of 6He(2+) to g=150
– Acceleration to near transition with a new 40 MHz RF
system
– Transfer of particles to the existing 200 MHz RF system
– Acceleration to top energy with the 200 MHz RF system
• Ejection in batches of four to the decay ring
Challenges:
• Transverse acceptance
Benasque
b
Decay ring
SPL
ISOL
Target
+ ECR
Linac,
cyclotron
or FFAG
Fast
cycling
synchrotron
PS
SPS
Decay
ring
Objective:
• Injection of 4 off-momentum bunches on a
matched dispersion trajectory
• Rotation with a quarter turn in longitudinal
phase space
• Asymmetric bunch merging of fresh
bunches with particles already in the ring
Benasque
Injection into the decay ring
b
• Bunch merging requires fresh bunch to be injected at ~10 ns
from stack!
– Conventional injection with fast elements is excluded.
• Off-momentum injection on a matched dispersion trajectory.
• Rotate the fresh bunch in longitudinal phase space by ¼ turn
into starting configuration for bunch merging.
– Relaxed time requirements on injection elements: fast bump
brings the orbit close to injection septum, after injection the
bump has to collapse within 1 turn in the decay ring (~20 ms).
– Maximum flexibility for adjusting the relative distance bunch to
stack on ns time scale.
Benasque
Horizontal aperture layout
• Assumed machine and beam parameters:
–
–
–
–
–
Dispersion:
Beta-function:
Moment. spread stack:
Moment. spread bunch:
Emit. (stack, bunch):
Dhor
bhor
Dp/p
dp/p
egeom
b
= 10 m
= 20 √m
= ±1.0x10-3 (full)
= ± 2.0x10-4 (full)
= 0.6 pmm
Beam: ± 2 mm momentum
± 4 mm emittance
Septum & alignment 10 mm
Required bump:
22 mm
Stack: ± 10mm momentum
Required separation:
30 mm, corresponds to
3x10-3 off-momentum.
± 4 mm emittance
22 mm
Central orbit undisplaced
M. Benedikt
Benasque
Full scale simulation with SPS as model
• Simulation conditions:
– Single bunch after injection and ¼ turn rotation.
– Stacking again and again until steady state is reached.
– Each repetition, a part of the stack (corresponding to
b-decay) is removed.
• Results:
– Steady state intensity was ~85 % of theoretical value
(for 100% effective merging).
– Final stack intensity is ~10 times the bunch intensity
(~15 effective mergings).
– Moderate voltage of 10 MV is sufficient for 40 and 80
MHz systems for an incoming bunch of < 1 eVs.
Benasque
b
Stacking in the Decay ring
• Ejection to
matched dispersion
trajectory
• Asymmetric bunch
merging
Benasque
b
SPS
Asymmetric bunch merging
b
Benasque
Asymmetric bunch merging
b
0.5
0.4
0.3
A
0.2
0
0.1
5
10
15
Iterations
20
25
0
8.17
11
10
0.6
0.5
e eVs
4
0.4
A
0.3
2
0.2
0
0
0.1
MeV
5
10
15
Iterations
20
25
0
0
8.52
11
10
7.5
2
e eVs
0.4
4
5
0.3
0
MeV
0.0585 eVs
matched
0.298 eVs
2 prms p
1.2 10 3
BF
0.1
0
10
0
20
30
Iterations
40
50
0.16
0
Ne
1.57 10 11
fs0;1
822;790 Hz
e eV
8.16
11
10
4
2.5
e eVs
0.5
5
0.4
2
0.3
A
7.5
0
ns
rms
0.0583 eVs
matched
0.317 eVs
rms
2 p p
1.34 10 3
BF
25
50
0.2
0
MeV
0
25
1 104
50
2 104
75
0
0.1
5
0
0.14
10
15
Iterations
0
8.1
Ne
1.63 10 11
fs0;1
0;1060 Hz
10
11
e eV
100
3 104
125
4 104
2
e eVs
4
2
4
ns
Benasque
MeV
0
0
0.224
Ne
1.56 10 11
fs0;1
0;415 Hz
2
60
40
20
0
20
40
ns
rms
matched
2
rms
p
0.0639 eVs
0.323 eVs
1.25 10 3
p
BF
60
2 104
4
3 104
BF
0
0.168
Ne
1.6 10 11
fs0;1
823;790 Hz
e eV
0.0593 eVs
matched
0.333 eVs
2 rms
p
8.5 10 4
p
75
4 104
(S. Hancock, M. Benedikt and J,L.Vallet, A proof of principle of
asymmteric bunch pair merging, ABnote-2003-080 MD)
rms
50
1 104
25
2 104
0
3 104
25
e eV
50
4 104
75
5 104
100
6 104
rms
60
0
40
1 104
20
2 104
0
ns
3 104
20
4 104
40
0.2
A
2.5
60
Decay losses
• Losses during acceleration are being
studied:
– Full FLUKA simulations in progress for all
stages (M. Magistris and M. Silari, Parameters
of radiological interest for a beta-beam decay
ring, TIS-2003-017-RP-TN)
– Preliminary results:
• Can be managed in low energy part
• PS will be heavily activated
– New fast cycling PS?
• SPS OK!
• Full FLUKA simulations of decay ring losses:
– Tritium and Sodium production surrounding rock well below national
limits
– Reasonable requirements of concreting of tunnel walls to enable
decommissioning of the tunnel and fixation of Tritium and Sodium
Benasque
b
Decay losses
b
• Acceleration losses:
6He
(T1/2=0.8 s)
Accumulation <47 mW/m
Benasque
18Ne
(T1/2=1.67 s)
<2.9 mW/m
PS
1.2 W/m
90 mW/m
SPS
0.41 W/m
32 mW/m
Decay ring
8.9 W/m
0.6 W/m
A. Jansson
How bad is 9 W/m?
• For comparison, a 50 GeV muon storage
ring proposed for FNAL would dissipate
48 W/m in the 6T superconducting
magnets. Using a tungsten liner to
– reduce peak heat load for magnet to 9 W/m.
– reduce peak power density in superconductor
(to below 1mW/g)
– Reduce activation to acceptable levels
• Heat load may be OK for superconductor.
Benasque
b
SC magnets
b
• Dipoles can be built
with no coils in the
path of the decaying
particles to minimize
peak power density in
superconductor
– The losses have been
simulated and one
possible dipole design
has been proposed
S. Russenschuck, CERN
Benasque
Tunnels and Magnets
• Civil engineering costs: Estimate of 400 MCHF for 1.3%
incline (13.9 mrad)
– Ringlenth: 6850 m, Radius=300 m, Straight sections=2500 m
• Magnet cost: First estimate at 100 MCHF
FLUKA simulated losses in surrounding rock (no
public health implications)
Benasque
b
Intensities
b
Stage
6He
18Ne (single target)
From ECR source:
2.0x1013 ions per second
0.8x1011 ions per second
Storage ring:
1.0x1012 ions per bunch
4.1x1010 ions per bunch
Fast cycling synch:
1.0x1012 ion per bunch
4.1x1010 ion per bunch
PS after acceleration: 1.0x1013 ions per batch
5.2x1011 ions per batch
SPS after
acceleration:
0.9x1013 ions per batch
4.9x1011 ions per batch
Decay ring:
2.0x1014 ions in four 10
ns long bunch
9.1x1012 ions in four 10
ns long bunch
Only b-decay losses accounted for, add efficiency losses (50%)
Benasque
CERN to FREJUS
b
CERN
SPL @ CERN
2.2GeV, 50Hz, 2.3x1014p/pulse
4MW
Now under R&D phase
Benasque
40kt
400kt
Italy
The Super Beam
Benasque
b
6He

Beta-beam
boost
LOW-ENERGY BETA-BEAMS

b
C. Volpe, hep-ph/0303222
To appear in Journ. Phys. G. 30(2004)L1
THE PROPOSAL
To exploit the beta-beam concept to produce
intense and pure low-energy neutrino beams.
PHYSICS POTENTIAL
e
e C
N
Neutrino-nucleus interaction studies for particle,
nuclear physics, astrophysics (nucleosynthesis).
Neutrino properties, like  magnetic moment.
ABenasque
„BETA-BEAM“ FACILITY FOR LOW-ENERGY NEUTRINOS.
Prospects for the neutrino magnetic moment
6Li+e+
e
6He
6He
e e
e
E
e
Qb4. MeV

PRESENT LIMIT :
m < 1.0 x
10-10
mB.
b
5 X 10-11 mB
T
10-11 mB
e-e events with beta-beams
m=0
(10 15 /s) with a 4p low
threshold detector.
THE LIMIT CAN BE IMPROVED BY
-11 m ) .
ONE
ORDER
of
MAGNITUDE
(
a
few
x
10
B
Benasque
G.C. McLaughlin and C. Volpe, hep-ph/0303222, to appear in Phys. Lett. B.
Neutrino-nucleus Interaction Rates
At a Low-energy Beta-beam Facility
b
Neutrino Fluxes
Events/year for g=14
e + Nucleus Small Ring Large Ring
e + D
e + 16O
e + 208Pb
25779
82645
103707
1956
9453
7922
Small Ring :
Lss = 150 m, Ltot = 450 m.
Large Ring :
Lss = 2.5 km, Ltot = 7.5 km
INTERESTING INTERACTION RATES CAN BE OBTAINED.
Benasque
J. Serreau and C. Volpe, hep-ph/0403293, submitted to Phys. Rev. D.
Possible sites
GANIL
b
Intensities
g
Detectors
1012 /s
1
4p
1-10
4p and
A. Villari (GANIL)
GSI
109 /s
CERN
1013 /s
H. Weick (GSI)
(EURISOL)
Benasque
Autin et al,
J.Phys. (2003).
Close
detector
1-100
4p and
Close
detector
CERN IS A UNIQUE SITE BOTH FOR
THE -INTENSITIES AND THE -ENERGIES.
R&D (improvements)
SPL
ISOL
Target
+ ECR
Linac,
cyclotron
or FFAG
b
Rapid
cycling
synchrotron
PS
•
Production of RIB (intensity)
•
Acceleration (cost)
•
Tracking studies (intensity)
•
Superconducting dipoles (g of neutrinos)
SPS
Decay
ring
– Simulations (GEANT, FLUKA)
– Target design, only 200 kW primary proton beam in present design
– FFAG versa linac/storage ring/RCS
– High gamma option
– Loss management
– Pulsed for new PS/SPS (GSI FAIR)
– High field dipoles for decay ring to reduce arc length
– Radiation hardness (Super FRS)
Benasque
Comments & speculations:
Ne and He in decay ring simultaneously
• Possible gain in counting time and reduction of systematic
errors
b
– Cycle time for each ion type doubles!
• Requiring g=(60)150 for He will at equal rigidity result in a
g=(100)250 for Ne
– Physics?
– Detector simulation should give “best” compromise
• Requiring equal revolution time will result in a DR of 97(16)
mm (r=300 m)
– Insertion in one straight section to compensate
g Neon
Dr  r Neon
Benasque
AHelium

q Helium
ANeon
 g Helium
q Neon
b Neon  SS Helium
 SS Neon
 r Helium 
 r Helium  
 r Helium

b Helium  p
p

Comments & sepculations:
Accumulation Ne + He in DECAY RING
6He
Accumulation
(multiplication)
factor
8 s SPS
cycling
30
6He
25
16 s SPS
cycling
20
15
10
5
200
400
600
800
Requires larger long. Acceptance!
Benasque
1000
Time (s)
b
Comments & sepculations:
Accumulation Ne + He before acceleration
b
• Base line scenario assumes accumulation of 16
bunches for one second at 300 MeV/u (PS) for
both He and Ne
• Optimization assuming fixed ECR intensity (out):
– Longer accumulation
– SPS accumulation
1 s in baseline
Accumulation
(PS or SPS)
Benasque
Number of ions
constant from ECR
source
Production and
bunching (ISOL
and ECR)
Comments & speculations:
Accumulation before acceleration
25
20
b
SPS: Ne, one fill
of 1 unit of ions
every 1.2 s
PS
Baseline
15
10
SPS: He, one fill
of 1 unit of ions
every 1.2 s
5
5
10
15
20
25
30
Increase
of
intensity
Benasque
PS: Ne, one fill of 1
unit of ions every
1/16 s
Number of fills
PS: He one fill of 1 unit
of ions every 1/16 s
Comments & speculations:
Wasted time?
b
Ramp time
PS
Ramp
time SPS
Reset
time SPS
Decay
ring
SPS
PS
Production
Wasted time?
8
0
Benasque
Time (s)
Comments & speculations:
Higher Gamma?
•
b
Requires either a larger bending radius or a
higher magnetic field for the decay ring, the
baseline circumference is 6885 m and has a
bending radius (r) of 300 m:
• At g=500 (6He) , r=935 m at B=5 T
• To keep the percentage of straight section the same as
the baseline the ring would become 21.4 km long
• Alternatively new dipoles: r=300 m at B=15.6 T
• Or LHC type dipoles at B=10 T and r=468 m with a
circumference of 7794 m
• Requires an upgrade of SPS or ramping of the
decay ring
– SPS upgrade expensive and time consuming
– Ramping of decay ring requires less frequent fills
and higher total intensity
Benasque
Comments & speculations:
Duty factor (or empty buckets)
b
• The baseline delivers a neutrino beam
with an energy badly troubled by
atmospheric background
– Duty factor=4 10-4, 4 buckets out of 919
possible filled —› 10 ns total bunch
length
– At g=500 the duty factor can be
increased to 10-2 (P. Hernandez), 92
buckets filled or 23 times the intensity
theoretically, can that be realised?
Benasque
Comments & speculations:
Electron Capture, Monochromatic beams
b
• Nuclei that only decay by electron capture
generally have a long half-life (low Q value,
<1022 keV)
– Some possible candidates: 110Sn (4.1 h half life)
and 164Yb (75.8 min half life)
– Maybe possible if very high intensities can be
collected in the decay ring and a high duty
factor can be accepted (0.1)
• High gamma with ramping of the decay ring?
• For the baseline: With g=259, assuming 2.3 1016 ions in
the decay ring and a duty factor of 0.1 there would be
4 109 neutrinos per second at 259x0.326 MeV=84.434
MeV, is that useful?
Benasque
Design Study
USERS
Frejus
Gran Sasso
High Gamma
Astro-Physics
Nuclear Physics
(g, intensity and
duty factor)
b
EURISOL
OTHER LABS
Beta-beam Coordination
Beta-beam parameter group
Above 100 MeV/u
Targets
60 GHz ECR
Low energy beta-beam
And many more…
TRIUMF
FFAG
Tracking
Collimators
US study
Neutrino
Factory DS
Conceptual Design # with price ### M€
Benasque
Superbeam & Beta Beam cost estimates (NUFACT02)
Educated guess on possible costs
UNO
SUPERBEAM LINE
SPL
PS UPGR.
SOURCE (EURISOL), STORAGE RING
SPS
DECAY RING CIVIL ENG.
DECAY RING OPTICS
TOTAL (MCHF)
TOTAL (MUSD)
INCREMENTAL COST (MCHF)
INCREMENTAL COST (MUSD)
Benasque
b
USD/CHF
960
100
300
100
100
5
400
100
1.60
MCHF
MCHF
MCHF
MCHF
MCHF
MCHF
MCHF
MCHF
2065 MCHF
1291 MUSD
705 MCHF
441 MUSD
6He

Beta-beam
boost

b
A EURISOL/beta-beam facility
at CERN!
• A boost for radioactive nuclear
beams
• A boost for neutrino physics
“The chances of a neutrino actually hitting something as it travels
through all this emptiness are roughly comparable to that of
dropping a ball bearing from a cruising 747* and hitting, say an egg
sandwich”, Douglas Adams, Mostly Harmless, Chapter 3
*) European A380, Prototype will fly in 2005
Benasque
EURISOL Design Study, when will the beta-beam fly?