CINDY: The Proton Asymmetry in Neutron Decay

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(No Transcript)
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Magnetic field for PANDA Proton Asymmetry in
Neutron DecAy
For the SNS-FnPB Magnet meeting Prepared by Tim
Chupp
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The proton Asymmetry
e
e
p
p
n
n
N
N-
N - N- N N-
Asymmetry __________ C Pn A F (1-f)
Afalse
background
spin flip efficacy analyzing
power neutron polarization
gA gV
l 13 l 2
C k(AB) 4k ________
l ____
k0.27484
Standard Model
dW pe.pn
me J pe pn
pexpn
_____________ S(Ee) 1 a ______ b ___
___.(A____ B____ D _______ )
dEedWedWn
EeEn Ee J Ee En
EeEn
JTW-57
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C and l
l 13 l 2
C k(AB) 4k ________
sl l
sx x
PDG 2005
___
___ l -1.26950.0029 a -0.1030.004
0.2688 A -0.11730.0013 0.2403 B
0.983 0.004 1.385 C 0.238
0.011 1.430 D -0.00040.0006 f
180.060.0029
Abele, 2005
dW pe.pn
me J pe pn
pexpn
_____________ S(Ee) 1 a ______ b ___
___.(A____ B____ D _______ )
dEedWedWn
EeEn Ee J Ee En
EeEn
JTW-57
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Rudimentary Layout
By
For adiabatic neutron spin transport
Bx
M2
M1
Neutron spins tranported Through detector
polarizer
analyzer
Spin Flipper
X
N0(v)
y
neutrons
P(v) TP(v)
A(v) TA(v)
R
z
Detector
L
Detector 2
Detector 1
Neutron beam Into page
30 kV
V0




Allows proton spectroscopy
Detailed design work needed.
Uniform field B
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General Design Issues
Goal sx/x 10-3 or better

• Neutron spin transported adiabatically from
  polarizer to analyzer (through detector)
• Uniform B in decay region mitigates proton
  reflections from magnetic traps
• Proton orbit d 8 mm/B(T) 1-2T Needed (2 T for
  emiT proton segment
• Electrostatic proton energy resolution desired
  requirements on B in proton drift region TBA
• Vacuum requirements TBA

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Neutron Polarization and Polarimetry
M2
M1
polarizer
analyzer
Spin Flipper
X
N0(v)
neutrons
P(v) TP(v)
A(v) TA(v)
R
Detector
RExp S( ) D( - ) N0T1T2TP
G0DPR
GSD
M1 N0e1B1
M2 N0T1T2TPTAe3 1PAR B2
P/A Pn (5Å) Tn P2T features
PSM 99.x 10 0.1 fixed limited l
bite 3He (60) 80 30 0.2 flip P3 P3
varies
Flipper Ru 1 (unflipped) RfF-1 (flipped)
(-0.999 for AFP)
(M2u - M2f) (M2u M2f)
_________ PA(1-F) (1-f2)
BR (1 need to know to 0.1)
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Detector
L
Detector 2
Detector 1
Neutron beam Into page
30 kV
V0




Allows proton spectroscopy
Detailed design work needed.
Uniform field B
Ideal A1A21, e1e21, f1f20
Proton detection e.g. emiT2
with adiabatic spin transport JB with
adiabatic proton orbits, A1 (scattering
resid. gas, baffles, etc.)
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Statistics
rn 103/cm3
We expect about 0.5 decays per pulse about 2.5
million events per day. 0.1 precision requires lt
a few days NOT STATISTICS LIMITED Focus on
systematics
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Systematics
N - N- N N-
__________ C Pn A F (1-f) Afalse
background
spin flip efficacy analyzing
power neutron polarization
Need to know neutron polarization analyzing
power spin flip efficiency backgrounds
spin independent
spin dependent (false asymmetry)
e.g. False asymmetry from electrons emited from
n-decay (BR) - study of proton energy
dependence Noise, gain shifts, etc.
- flip 3He
C is INDEPENDENT of Pn, xy, L, tof, 3He, B, BR,
statistical power