Transcript Neutrino Factories

Neutrino Factory
Overview
Ken Peach
Particle Physics Department
A neutrino factory is …
… a medium energy
[10 GeV  50 GeV]
… high Intensity
[>1020 muon decays/year]
… muon storage ring
[racetrack, triangle, bow-tie]
… with long straight section(s)
… pointing to detector(s) several thousand km distant
… designed to measure the CP/T-violating phase in the MNS
matrix with good precision
Ken Peach
A neutrino factory is …
… an accelerator complex designed to produce >1020 muon
decays per year directed at a detector thousands of km away
Principal Components
High Power H- source
Proton
Target
Driver
Capture
‘far’ detector
(5000-8000km)
Cooling
Muon
Storage
Ring
Muon Acceleration
‘local’
detector
‘near’ detector (1000-3000km)
Ken Peach
Why?
• Neutrino physics has become a very hot topic
– Fundamental particle
– Recent observations show that neutrinos are not massless
– Neutrino masses are “something new”
• Physics “beyond the standard model”
– Implications for cosmology
– Possible (part of the) explanation for the matter/antimatter
asymmetry of the Universe
• Why is there a physical universe at all?
Ken Peach
The Neutrino Factory
CPV: > 1020 muon decays
Conventional n beams
p,m & K decay
Some flavour selectivity
Contamination
Fluxes ~1017-1018 n
Reactor n beams
Pure ne
Huge Fluxes
Very low energy (MeV)
Super Conventional n beams
p, (& some m) decay
Flavour selectivity (nm)
Low Contamination at E<200MeV
Fluxes ~1018-1019 n?
The Neutrino Factory
Ken Peach
Neutrino Mixing
U MNS 
s13ei   c12 s12 
1
  c13
 
 c s 

1


s
c
  12 12 
 23 23  
  s23 c23   s13ei
c13  
1
1


  ei / 2


ei / 2 
1
 2


0
.
13
3
 3

1
1

   16
3
2
 1

1
1

3
2 
 6
Parameters of neutrino oscillation
1 absolute mass scale
mν e
2 squared mass differences Δm221 , Δm232
2
2
2

Δm ji  m j  mi

2
2
2

Δm31  Δm32  Δm21
3 mixing angles
θ12 , θ 23 , θ13
1 phase
δ ( alw ays s inθ13 eiδ )
2 Majorana phases
α,β
2
m32
 (2.6 0.4)10-3 eV2
2
m21
 (7.3 0.8)10-5 eV2
Ken Peach
Neutrino matter-antimatter asymmetry
PCPodd n e  n m ) 
1
2
cos13 )sin 213 )sin 2 23 )sin 212 )
sin
 )sin  )sin )
2
m21
L
2E
2
2 m32 L
4E
L/E
Ken Peach
Matter v. CP-violation effects
Ken Peach
A neutrino factory provides …
flavour tagged
background free
normalised (calibrated flux)
equal flux
beams of
muon antineutrinos and electron neutrinos from m+
muon neutrinos and electron antineutrinos from mIn principle, gives a complete set of measurements
n e, n m  n x
ne  nm
n e, n m  n t
m m
disappearance
appearance
appearance
and
charge conjugate
Ken Peach
Shape of Muon Storage Ring
• Racetrack
– Single far detector, relatively simple construction
• Maximum ‘efficiency’ ~ 40%
• Very intense local beam for conventional neutrino experiments
• Triangle
– Two detectors at different distances
• (~1000km, ~3000km or ~3000km, ~6000km)
• Maximum ‘efficiency’ ~80%
– Ring built in a steeply inclined plane
– Steeply rising local beam for conventional neutrino experiments
• Bow-tie
– Advantages as for triangle
• Because of the ‘bow-tie’, the depth is ~½ triangle depth
– 2 Steeply rising local beams for conventional neutrino
experiments
– May ruin the precision knowledge of the neutrino spectrum
Ken Peach
Where could a neutrino factory be
built?
FNAL
BNL
DUBNA
JHF
CER
N
GSI
CEA
INFN
Ken Peach
Possible Baselines
Gruber
Ken Peach
Proton or H- Source and Proton Driver
• Pion production in the 200 - 400 MeV region is
essentially proportional to the beam power over a
wide range of proton energies
– 1-5 MW beam power required for 1020  1021 muons per year
– mA proton currents required
• Proton energy is a critical design choice
– Ideas at 2.2 GeV (CERN), 5 GeV (RAL), 8 & 16 GeV (FNAL),
15 GeV (CERN), 24 GeV (BNL), 50 GeV (JHF)
– ‘figure of merit’ is probably
• pions per steradian per proton per GeV
– Part of the overall design optimisation
• Need better data on pion production
– HARP, E910
Ken Peach
Example: Proton Driver Design
75 keV
H
LEBT
2.493 MeV
280 MHz RFQ
Ion Source
Chopper
180.2 MeV
280 MHz DTL
Section
Similar features needed for
•
ESS
•
Radioactive Ion Beams
•
Accelerator Transmutation
of Nuclear Waste
•
IFMIF
Prior & Rees
Ken Peach
The proton power of a neutrino factor
Ken Peach
Pion Source & Decay Channel
Solenoid option – alternative magnetic horn
Ken Peach
Target issues/muon source
• Liquid jet … or … solid
(moving?) target
– no clear consensus
• much R&D needed
– Existing/future high
power targets
• RAL/ISIS
• CERN/ISOLDE
• CERN &
FNAL/antiproton
• SNS/Oak Ridge
• FNAL/NuMI
• PSI,TRIUMF &
KEK/muon sources
– clear area for R&D
Mohkov (FNAL)
• material
• radiation & heating
Ken Peach
Target Studies for a Future Neutrino Factory
Pion production target for a future neutrino factory:
Pulsed proton beam induced shock waves in section
of solid tantalum target
Proposed rotating tantalum target ring
Temperature jump (cut-away section
of target material)
Shock wave stresses
Shock wave stress
intensity contours 4 µs
after 100 kJ, 1 ns
proton pulse
Roger Bennett, Chris Densham & Paul Drumm
Ken Peach
PULSED EFFECTS
Slow target rotation - areas illuminated by pulses overlap
Proton beam pulse length
(~1 ns) at 100 Hz rate.
 rotation
individual overlapping beam pulses on the target, 20 cm long
Faster rotation, illumination by each pulse separate until at v = 20 m/s they just touch.
At speeds greater than 20 m/s the areas of each pulse separate
The maximum power at a pulse repetition rate
f is:
W = 0.322·f
W = 32 MW at 100 Hz
Roger Bennett, Chris Densham & Paul Drumm
Ken Peach
POWER DISSIPATION
1 10
3
1000 m
100
100 m
200 m
10 m
20 m
2000 m
v = 20 m/s
1000 m v = 10 m/s
10
power
v = 100 m/s
10000 m
100 m
v = 1 m/s
MW
1
2m
1m
10 m
100 m
10 m
v = 0.1 m/s
1m
10 m
0.1
1m
0.1 m
0.01
0.01
0.1
0.1 m
1
Roger Bennett, Chris Densham & Paul Drumm
10
100
1 10
3
radius/velocity
Ken Peach
Cooling
• Cooling will (probably) work
… but experiments needed
pions longitudinal phase space at production. (fluka
calculation, 26 mm mercury target, 2.2 GeV beam)
Lombardi
Ken Peach
One Challenge: Ionization Cooling
After Multiple
Scattering
Muon Momentum
After ionisation
energy loss
PT
After Acceleration
PL
Ken Peach
Heating and Cooling
Zisman
Ken Peach
Muon Ionisation Cooling Experiment
Ken Peach
ISIS as MICE host
HEP Test
Beam Hall
Potential
MICE
location
An international
study of muon
beam options
(including CERN,
FNAL, TRIUMF,
PSI) ISIS was
identified as the
best technical
location for the
MICE test facility
Ken Peach
Ionisation loss
Zisman
Ken Peach
Muon Ionisation Cooling Experiment
What does it have to do?
• Demonstrate a cooling channel is feasible
• Measure a 10% reduction in emittance
• Investigate channel performance as a function of
 Emittance: 1πmm.mrad to 50 πmm.mrad
 Energy: 100 to 400 MeV
 Energy spread: “zero” to 20%
 Phase, B-field, etc?
• Use a single particle beam
Ken Peach
m
-
STEP I:
2004
STEP II:
summer 2005
STEP III:
winter 2006
STEP IV:
spring 2006
STEP V:
fall 2006
STEP VI:
2007
Blondel
Ken Peach
Reverse Rotation Lattice
An alternative to cooling?
Pion-muon decay channel
88 MHz muon linac
Chris Prior, Graham Rees
Ken Peach
Muon Acceleration
• 2 or 3 stages
– Linac (to 1  2 GeV?)
– Recirculating linac 1 (to 10 GeV?)
– Recirculating linac 1 (to final energy)
• Some possible parameters (CERN)
Haseroth
Ken Peach
Muon Storage Ring
• A design (CERN)
Haseroth
Ken Peach
Cost breakdown - subsystems
% cost
Storage Ring
RLA2
Capture Linac
Cooling Channel
% cost
Capture+Mini c.
Induction Linac
Decay Channel
Target Systems
Proton Driver
0.0%
5.0%
10.0%
% cost
15.0%
20.0%
25.0%
30.0%
Civil
ES&H
Utilities
Components
Sub-system
FNAL Feasibility study
RLA 1
Cryo
Diagn.
% cost
PS
Vacuum
RF Cav
RF Source
Magnets
0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
Ken Peach
Where could a neutrino factory be
built?
FNAL
BNL
DUBNA
JHF
CER
N
GSI
CEA
INFN
Ken Peach
Neutrino Factory
Neutrino Factory Footprint
Ken Peach
Encouragement
Research Fortnight, 15th January 2003
House of Commons Science and
Technology Select Committee.
First Report on the work of PPARC,
17th December 2002
“Hosting a global facility like the neutrino
factory would bring substantial scientific
and commercial benefits to the UK”
‘the government will need to show “greater
willingness” … to carry out the necessary
development work to put together a
serious bid, and then commit the
necessary resources … to see it through’
“We believe that an ambitious and far
sighted approach is needed to secure
maximum benefit for UK science”
Ken Peach
A neutrino factory …
… is needed (probably) to measure CP violation in the
lepton sector
… is (probably) feasible
… but significant challenges
Design
Machine
Detector
– muon energy, baseline optimisation
– target, cooling, r/f (muon acceleration)
– flavour identification with charge measurement
… and COST
Ken Peach