Status Report for KEK-PS E391a KEK IPNS G.Y.Lim 14 April 2003.
PRISM and Neutrino Factory in Japan Y. Kuno KEK, IPNS January 19th, 2000 at CERN.
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Transcript of PRISM and Neutrino Factory in Japan Y. Kuno KEK, IPNS January 19th, 2000 at CERN.
PRISM and Neutrino Factory
in Japan
Y. KunoKEK, IPNS
January 19th, 2000at CERN
PR
ISM
What is PRISM ?
PRISM (Phase Rotation Intense Slow Muon source)
= a dedicated secondary muon beam channel with high intensity and
narrow energy spread for stopped muon experiments.
PRISM Scheme
pulsed proton beam pion capture by high solenoid fiel
d pion decay section phase rotation section
PRISM Beam
Characteristics
intensity : 1011-1012±/sec muon kinetic energy : 20 MeV (=68 MeV/c)
– range = about 3 g kinetic energy spread : ±0.5-1.0
MeV– ±a few 100 mg range width
beam repetition : about 1 kHz
– in terms of muon lifetime, a 100kHz -1 MHz is ideal.
– increase in future, if technically possible.
Summary
PRISM would be a unique and novel facility in the world, born in Japan. It is attracting much attensions in the worldwide.
A search for muon LFV violation is one of main topics at PRISM, in particular -e conversion.
Applications like biology etc. might as well be incorporated.
Most of technology is in hand, but need some prototyping.
A design note by May, 2000 ? Cost estimation ?
We are hoping to construct PRISM by the time when the 50-GeV PS will be on.
maximum transverse momentum
– R : radius of magnet– ex: H=120kG(=12T), R=5cm
» PT < 90 MeV/c
capture yields
Pion Capture Yield
PT(MeV / c) =0.3×H(kG) ×R2⎛⎝
⎞⎠(cm)
low energy pions
for 50GeV protons
0.2 pions/proton
Guide Lines of SC Solenoid
Magnet
Configuration– A hybrid solenoid magnet of 10-12 T
at 4.2 K– Radiation shield with water cooling
Coil cooling– conductive cooling with high heat-tra
nsfer path– heat load < a few 10 W (goal)
Cryogenics– cryo-cooler in parallel operation or re
frigerator with remote heat exchanger.
– located at a few meter away from the coil.
Phase Rotation = decelerate particles with high energy and accelerate particle with low energy by high-field RF
A narrow pulse structure (<1 nsec) of proton beam is needed to ensure that high-energy particles come early and low-energy one come late.
Phase Rotation
energyenergy
time time
important
Phase Rotation Simulation
simulation with rf kicks
after phase rotation
before phase rotation
Why FFAG for Phase Rotation ?
a ring instead of linear systems– reduction of # of rf cavities– reduction of rf power comsumption– compact
(Fixed Field Alternating Synchrotron) synchrotron oscillation for phase rotatio
n– not cyclotron (isochronous)
large momentum acceptance– larger than synchrotron– ± several 10 % is aimed
large transverse acceptance– strong focusing– large horizontal emittance– reasonable vertical emittance at low energy
PRISM layout
not in scale
Phase Rotation Simulation at FFAG(1)
non-linear relation on energy vs. time at low energy
in case of sin-wave rf– after 5 turns
dp/p
(%)
phase (degree)
Phase Rotation Simulation at FFAG (2)
in case of saw-tooth wave rf
phase (degree)
dp/p
(%)
PRISM at the 50-GeV PS
why at the 50-GeV PS?– a narrow bunched proton beam
is needed. in the 50-GeV PS
experimental hall
Muon Yield Estimation at PRISM
muon yield – PT<90 MeV/c (12T 5cm radius) at p
ion capture– 3000 mm ・ mrad vertical accepta
nce of FFAG
in 20 MeV±(0.5-1.0)MeV range proton intensity at the 50-GeV PS
– 1014 proton/sec muon yield
– 1011-1012 ±/sec
0.005 - 0.01 ±/proton
OK!
How
, Mu
on L
FV
?
Status of Muon LFV
Experimental status
• 1) PSI experiment (2003)• 2) PSI experiment (running)• 3) BNL-E940 (MECO) experiment (2003)
Muon LFV at PRISM– the best for -e conversion
» a pulsed beam needed.– eeee
» continuous beam needed to reduce accidental background.
– muonium to anti-muonium conversion
» a pulsed beam is needed.
current limitsnear futurePRISM
μ+ → e+γ <1.2×10−11 <10−14 1) <10−15
μ+ → e+e+e− <1.0×10−12 none <10−15
μ−N → e−N <6.1×10−13 <10−14 2) <10−18
<10−16 3)
econversion in a Muonic Atom
muonic atom (1s state)
neutrinoless muon nuclear capture (=-e conversion)
muon decay in orbit
nucleus
−→ e−ν ν −+ (A, Z) → ν μ + (A,Z −1)
nuclear muon capture
−+ (A, Z) → e− + (A,Z )
lepton flavors changes by one unit.
B(−N→ e−N) =Γ(−N → e−N)Γ(−N → νN')
coherent process
econversion:Signal and Background
coherent conversion (Z5)
Event Signature– single mono-energetic electron of (m-B) M
eV Backgrounds
– no accidental background– muon decay in orbit (E)5)
» highest endpoint comes to the signal
– radiative muon capture with photon conversion
– pion capture with photon conversion» to remove pions in beam, a pulsed beam is usefu
l, where the measurement waits until pions decay.
– cosmic ray
−+ (A, Z) → e− + (A,Z )
MECO at BNL/AGS
E940 aim at B(AleAlat BNL AGS MECO
5x1011-/pulse, 1.1MHz pulse– 8GeV proton beam at AGS – high field capture solenoid of 4T
schedule : 2003 start ???
PRISM Beam Requirement
for -e conversion
higher muon intensity– 1012 -/sec
pulsed beam– background rejection
narrow energy spread– allow a thinner muon-stopping taret
» better e- resolution and acceptance» point source
– allow a beam blocker behind the target
» isolate the target and detector» tracking close to a beam axis
less beam contaminations– no pion contamination
» long flight path at FFAG (150 m)
– beam extinction between pulses» kicker magnet at FFAG
targ
et
bloc
ker
SC
sole
noid
magnet
trig
ger
counte
rtr
ack
ing c
ham
ber
106
MeV
ele
ctro
n
not
in s
cale
muo
n be
amfro
m P
RISM
a m
agneti
c field
is
gra
ded a
t th
e t
arg
et
regio
n.
(deta
ils a
re n
ot
dete
rmin
ed)
Improvement of Signal Sensitivity
PRISM MECOStopped
muons/sec1012/sec(x4 times protons in future)
1011/sec
Target
material
Ti Al
Target
arrangement
Single 0.005 cm plate
or
10 layers of 5 mplates
(17-25)layers of 0.05cm
plate
e-momentum
resolution
σRMS=100keV σRMS=150keV
e-detection
soli d angle
40% <20%(45<θ<62)
e- signal
acceptance
(response
function)
No tails
100 %
Tail due to energy loss
<50 %
Time window Full time window
100 %
Delayed window
50 %
B(μA→ eA)/ B(μ→ eγ)≈1/ 238 B(μA→ eA)/ B(μ→ eγ)≈1/389
100 cm
time time
energy energy
econversion:Muon Decay in Orbit
Muon decay in orbit ((Ee-Ee)5)– required e+ momentum resolution is determined
(100-200 keV) at 10-18 sensitivity
present limit
MECO goal
JHF goal
signal
Wh
at E
lse
from
PR
ISM
?
More Physics Lists with PRISM
muon (g-2)– muon momenum = 3 GeV/c– small beam may improve the sensiti
vity further.– muon polarization
muon EDM– muon momentum = 500 MeV/c– high intensity and small beam shoul
d improve the sensitivity.– muon polarization
muonium to anti-muonium conversion
muon lifetime muonium spectroscopy muonic atom spectroscopy
Application List with PRISM
Brain scan studies– muonic X-ray measurement.– - beam from PRISM with small stop
ping region. trace-element analysis
– living cells biology materials science nsec response spectroscopy with
muons.– phase rotation to make narrow time
width (instead of narrow energy spread).
time
Future studies on PRISM
muon polarization– with cost of muon intensity, can imp
rove muon polarization ? muon cooling
– can muon be cooled at PRISM ? – precooling by H2
– higher than 300 MeV/c– high rf gradient needed.
Additional acceleration– to an muon EDM ring ?
» 100-500 MeV/c– to a muon g-2 ring ?
» 3 GeV/c (magic momentum)– cooling or no-cooling ??
from
PR
ISM
to
neu
trin
o fa
ctor
y
Neutrino FactoryNeutrino Factory
Oscillation Signature at Neutrino Factory
Oscillation signature
charge identification needed.– +/ is easy.– e+/e is difficult.
μ− → e− ν e νμ
ν μ
μ−
μ+
oscillation
μ+ → e+ νe ν μ
νμ
μ+
μ−
oscillation
Advantages of Neutrino factory
…...compared with a neutrino source of pion decays,
large neutrino intensity at high energy– 2x1020 neutrinos/year (1020-1022) – about 100 times intensity at a few 1
0 GeV energy range extremely low backgrounds
– 10-5 to 10-6 level (charm background)
» a few % level at the pion sources. precise knowledge on neutrino int
ensity and emittance
Event Rates
CC event rate
Oscillation rate
higher energy, better…. a number of CC events/year
– 1021muons/year in the ring– for a 10 kton detector
LÅÅÇPÇOÇOÇOkm LÅÅÇPÇTÇOÇOkm
E=20 GeV 3 .2 10x 5 1 .4 10x 5
E=30 GeV 1 .1 10x 6 4 .8 10x 5
a la O.Yasuda
NCC(νe → e)∝θν2 ⋅σ ∝
Eμ2
L2 ⋅Eμ =Eμ
3
L2
Nosc(νe → μ)∝θν2 ⋅σ ⋅P(νe → νμ )
∝Eμ
3
L2 ⋅L2
Eμ2 =Eμ
Oscillation Probabilities
when
measurement of– appearance measurement, for insta
nce,– sensitivity is determined by backgou
nd level (10-5-10-6)» a la Juan Jose Gomez Cadenas
– enhancement of matter effect
Δm212 <<Δm32
2
P(νe → νμ) =sin2(2θ13)sin2(θ23)sin2 1.27Δm322 L
Eν
⎛
⎝ ⎜
⎞
⎠ ⎟
P(νe → ντ ) =sin2(2θ13)cos2(θ23)sin2 1.27Δm322 L
Eν
⎛
⎝ ⎜
⎞
⎠ ⎟
P(νμ → ντ ) =cos4(θ13)sin2(2θ23)sin2 1.27Δm322 L
Eν
⎛
⎝ ⎜
⎞
⎠ ⎟
θ13
P(νe → νμ)
Wrong Sign Muons: P(νeν1
Δm322 =2×10−3eV2
θ13 =1o
θ13 =9o
Wrong Sign Muons: P(νeν2
Δm322 =3.5×10−3eV2
θ13 =1o
θ13 =9o
Wrong Sign Muons: P(νeν3
Δm322 =6×10−3eV2
θ13 =1o
θ13 =9o
Opportunity of Neutrino Factory at 50-
GeV PS
A possible opportunity in Japan will be based on the case of the 50-GeV PS, as an existing proton driver.– 1st phase: 0.75 MW– 2nd phase: 4 MW??
If the 50-GeV PS is already available, construction of a neutrino factory is very cost-effective.
The PRISM (= a low-energy muon source) experience will be directly and effectively extended towards a
neutrino factory.
a factor of only 20!
Towards Neutrino Factory
at the 50-GeV PS
increase of muon yield– 1019 ±/year for PRISM– 2x1020 ±/year for a neutrino factory – possible improvements are
» higher capture magnetic field» pions capture of higher momentum » forward extraction at the target» precooling and after-cooling , etc.
increase of proton intensity at the 50-GeV PS– 1014 protons/sec for Phase-I– 5x1014 protons/sec for Phase-II
increase the detector size– cheeper than accelerator– an event yield is the product of bea
m intensity and detector size.
Long Baseline from 50-GeV PS
long baseline
Fuku
oka
(10
00
km)
Sh
an
gh
ai(
20
00
km)
Kam
ioka
(250
km)
Toka
i
Summary
PRISM would be a unique and novel facility in the world, born in Japan. It is attracting much attensions in the worldwide.
A search for muon LFV violation is one of main topics at PRISM, in particular -e conversion.
Applications like biology etc. might as well be incorporated.
Most of technology is in hand, but need some prototyping.
A design note by May, 2000 ? Cost estimation ?
We are hoping to construct PRISM by the time when the 50-GeV PS will be on.
Summary
PRISM experience is important towards a neutrino factory at the 50-GeV PS.
If the 50-GeV PS is given, a neutrino factory could be built cost-effectively in future.
A factor of about 20 is needed from PRISM intensity to achieve 2x1020/year.– a factor of 5 from the 50-GeV PS upgrade in
Phase-II– some modest efforts in improvement of mu
on yield– a larger detector (cheeper than acceleraor)
Quick start should be aimed with reasonable performance.– optimize just or a neutrino factory , and do
not aim too high for a muon collider.