Neutrino Factory Overview
-
Upload
natalie-brown -
Category
Documents
-
view
44 -
download
1
description
Transcript of Neutrino Factory Overview
Ken Peach
Particle Physics Department
Neutrino Factory Overview
Ken Peach
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 designed to measure the CP/T-violating phase in the MNS matrixmatrix with good precisionwith good precision
Ken Peach
Muon
Storage
Ring
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- sourceProton
DriverTarget Capture
Co
olin
g
Muon Acceleration
‘near’ detector (1000-3000km)
‘far’ detector (5000-8000km)
‘local’ detector
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 decaysConventional beams
& K decaySome flavour selectivityContaminationFluxes ~1017-1018
Reactor beamsPure e
Huge FluxesVery low energy (MeV)
Super Conventional beams(& some decay
Flavour selectivity ()Low Contamination at E<200MeVFluxes ~1018-1019
The Neutrino Factory
Ken Peach
2/
2/
1212
1212
1313
1313
2323
2323
1
1
1
1
i
i
i
i
MNS
e
e
cs
sc
ces
esc
cs
sc
U
Neutrino Mixing
Parameters of neutrino oscillation
1 absolute mass scale
2 squared mass differences
3 mixing angles
1 phase
2 Majorana phases βα,
)esinθ always ( δ
θθθ
ΔmΔm
m
iδ13
132312
232
221
νe
, ,
,
221
232
231
2i
2j
2ji
ΔmΔmΔm
mmΔm
21
31
61
21
31
61
31
32 13.0
25-221
2-3232
eV10 0.8)(7.3
eV10 0.4)(2.6
m
m
Ken Peach
Neutrino matter-antimatter asymmetry
L/E
sinsinsin
2sin2sin2sincos
42
2
1223131321
232
221
ELm
ELm
eCPoddP
Ken Peach
Matter v. CP-violation effects
Ken Peach
A neutrino factory provides …
flavour tagged background free normalised (calibrated flux)equal fluxbeams of
muon antineutrinos and electron neutrinos from + muon neutrinos and electron antineutrinos from -
In principle, gives a complete set of measurements
e, x disappearance
e appearance
e, appearanceand
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?
FNALBNL
CERNGSICEAINFN
JHF
DUBNA
RAL?
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
Similar features needed for
• ESS
• Radioactive Ion Beams
• Accelerator Transmutation of Nuclear Waste
• IFMIF
H
Ion Source
LEBT 280 MHz RFQ Chopper 280 MHz DTL
2.493 MeV75 keV 180.2 MeV
Section
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• material• radiation & heating
Mohkov (FNAL)
>1 Tera Rad !
Ken Peach
Target Studies for a Future Neutrino Factory
Temperature jump (cut-away section of target material)
Shock wave stress intensity contours 4 µs after 100 kJ, 1 ns proton pulse
Pion production target for a future neutrino factory: Pulsed proton beam induced shock waves in section of solid tantalum target
Shock wave stresses
Proposed rotating tantalum target ring
Roger Bennett, Chris Densham & Paul Drumm
Ken Peach
PULSED EFFECTS
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.
Slow target rotation - areas illuminated by pulses overlap
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
0.01 0.1 1 10 100 1 103
0.01
0.1
1
10
100
1 103
power
MW
10 m
10 m
v = 100 m/s
1 m
1 m
100 m
100 m
0.1 m
200 m
20 m10 m
2 m
0.1 m
1 m
2000 m
1000 m
radius/velocity
v = 20 m/s
v = 10 m/s
v = 1 m/s
v = 0.1 m/s
1000 m
10 m
100 m
10000 m
Roger Bennett, Chris Densham & Paul Drumm
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
PT
PL
After ionisation energy loss
After Multiple Scattering
After Acceleration
Muon Momentum
Ken Peach
Heating and Cooling
Zisman
Ionization loss Multiple scattering
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
- 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
Pion-muon decay channel
88 MHz muon linac
Reverse Rotation Lattice
Chris Prior, Graham Rees
An alternative to cooling?
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 - subsystemsF
NA
L F
easi
bil
ity
stu
dy
Ken Peach
Where could a neutrino factory be built?
FNALBNL
CERNGSICEAINFN
JHF
DUBNA
RAL?
Ken Peach
Neutrino Factory
Neutrino Factory Footprint
Ken Peach
Encouragement
Research Fortnight, 15th January 2003
“Hosting a global facility like the neutrino factory would bring substantial scientific
and commercial benefits to the UK”
“We believe that an ambitious and far sighted approach is needed to secure
maximum benefit for UK science”
‘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’
House of Commons Science and Technology Select Committee.
First Report on the work of PPARC,
17th December 2002
Ken Peach
A neutrino factory …
… is needed (probably) to measure CP violation in the lepton sector
… is (probably) feasible
… but significant challenges
Design – muon energy, baseline optimisationMachine – target, cooling, r/f (muon acceleration)Detector – flavour identification with charge measurement
… and COST