Transcript The Neutron Alphabet Hartmut Abele Exploring the properties of fundamental interactions with

The Neutron Alphabet
Exploring the properties of
fundamental interactions with cold neutrons
Hartmut Abele
The Neutron Alphabet and Symmetries
A
Electron

Neutron Spin
B
Neutrino
C
Proton
Hartmut Abele, University of Heidelberg
A: P-odd
B: P-odd
C: P-odd
D: T-odd
a
N
R: T-odd
2
Experimental Groups, Neutron b-Decay
New experiments are greatly profiting from
new sources & techniques
Talks at NIST workshop from different groups in 2004:
Hartmut Abele, University of Heidelberg
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Facilities
2.0
Nico, Snow, Annu Rev Nucl Part Sci 55 (2005) 55
Hartmut Abele, University of Heidelberg
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Facilities
Nico, Snow, Annu Rev Nucl Part Sci 55 (2005) 55
Hartmut Abele, University of Heidelberg
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Nuclear and Particle Physics
Neutrograph,
Radio- and Tomography station
Hartmut Abele, University of Heidelberg
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1. Polarizer
The PERKEO II Setup @ ILL
M. Schumann 2006
2. Spin Flipper
3. Spectrometer
Hartmut Abele, University of Heidelberg
4. Beam Stop
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The new Polarizer: 99.7 % Efficiency
Kreuz, Soldner, Pekoutov, Nesvizhevsky, NIM 2006
100 %
96 %
ILL, HD
A new geometry for Beam
polarization
Towards a perfectly polarized
neutron beam
94 %
Status
2002
W a
a
2

nucl
m ag
90 %
100 %
W W 
Spin up: reflected
P  
1
W  W 
Spin down: absorbed
98 %
Coherent nuclear (strong)
and electronic (magnetic) scattering
W   a nucl  a m ag
2
96 %
95 %
Hartmut Abele, University of Heidelberg
Status 2004
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Rf Spin flipper: 100% efficiency
T. Soldner & A. Petoukhov
Lab frame
Rotating frame
Rotating frame
Hartmut Abele, University of Heidelberg
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Cold Neutrons
For Correlation Coefficient A Measurements…
High Flux:  = 2 x 1010 cm-2s-1

Decay rate of 1 MHz / meter / sec
Count rate:
Polarized to 98%:
Polarized to 99.7%:
Pulsed/unpulsed
106 s-1
2.5 x 105 s-1
1.4 x 105 s-1
Spectrometer
Hartmut Abele, University of Heidelberg
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Experiments
Hartmut Abele, University of Heidelberg
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Characteristics
of Experiments
Using
Magnetic Fields
PERKEO III

Hartmut Abele, University of Heidelberg
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PERKEO III
20 October 2006 – 11 April 2007
Small systematic errors
- background
- edge effect
- mirror effect
B. Maerkisch, D. Dubbers, H.A. et al.
Hartmut Abele, University of Heidelberg
to beamstop
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PERKEO III
Hartmut Abele, University of Heidelberg
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Hartmut Abele, University of Heidelberg
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Hartmut Abele, University of Heidelberg
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Hartmut Abele, University of Heidelberg
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Hartmut Abele, University of Heidelberg
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Aim: Weak Magnetism form factor f2
Neutron Decay Transition Matrix:
Tfi 
GF
Vud  p |   (1   5 ) | n  (  (1   5 )e)
2
V  p [ f1 (k 2 )  
2
f 2 (k )
  k  if3 (k 2 )k ]| n
2m p
f2 Weak Magnetism Form Factor
(SM prediction)
Electron Asymmetry:
2 % additional Edependence of A
PERKEO III can deliver the necessary statistics!
Hartmut Abele, University of Heidelberg
Talk Marc Schumann at ILL
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a Spect, Univ. MZ/TUM
Proton spectroscopy
Hartmut Abele, University of Heidelberg
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First impression
aSPECT is a retardation spectrometer for protons of free neutron decay
aSPECT
Hartmut Abele, University of Heidelberg
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PNPI Experiment
Hartmut Abele, University of Heidelberg
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aCORN
Surface barrier
detector
Hartmut Abele, University of Heidelberg
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Hartmut Abele, University of Heidelberg
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D-Coefficient
emiT
Trine
Hartmut Abele, University of Heidelberg
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Nab
Electron and neutrino momenta from electron
energy
cose from proton momentum and electron energy
using
4T  1T
TOF between electron and proton
Hartmut Abele, University of Heidelberg
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UCNA Collaboration
California Institute of Technology
R. Carr, B. Filippone, J. Hsiao, R. McKeown, B. Plaster, B. Tipton, J. Yuan
Institute Lau-Langevin
P. Geltenbort
Idaho State University
R. Rios, E. Tatar
Los Alamos National Laboratory
J. Anaya, T. J. Bowles (co-spokesperson), T. Brun, M. Fowler, R. Hill, G. Hogan, T. Ito, K. Kirch, S.
Lamoreaux, M. Makela, C. L. Morris, A. Pichlmaier, A. Saunders, S. Seestrom, P. Walstrom
North Carolina State University/TUNL
H. O. Back, L. Broussard, A. T. Holley, R. K. Jain, R. W. Pattie, K. Sabourov, A. R. Young (cospokesperson), Y.-P. Xu
Petersburg Nuclear Physics Institute
A. Aldushenkov, A. Kharitonov, I. Krasnoshekova, M. Lasakov, A. P. Serebrov, A. Vasiliev
Tohoku University
S. Kitagaki
University of Kyoto
M. Hino, T. Kawai, M. Utsuro
University of Washington
A. Garcia, S. Hoedl, D. Melconian, A. Sallaska, S. Sjue
University of Winnipeg
J. Martin
Virginia Polytechnic Institute and State University
R. Mammei, M. Pitt, R. B. Vogelaar
Hartmut Abele, University of Heidelberg
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Results: A
A
Neutron Spin
Electron
Hartmut Abele, University of Heidelberg
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Results PERKEO II
(2006)
Spectra
Dissertation D. Mund, 2006
Hartmut Abele, University of Heidelberg
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Result for A
Aexp
Aexp
N  N
 
N  N
1 v
 A Pf
2 c
N  N
 
N  N
1 v
 A Pf
2 c
 (   1)
A  2
1  3 2
Hartmut Abele, University of Heidelberg
Dissertation D. Mund, 2006
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Beamrelated Background
Collimation system
< 0.15 s-1
ElectronSpectrum
Beamline BG
Det. 0
Det. 1
Fitregion
Hartmut Abele, University of Heidelberg
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2002
2002
2006
2006
correction uncertainty correction uncertainty
polarization
flipper efficiency
1.1 %
0.3 %
Statistical error
background
detector function
edge effect
time resolution
mirror effect
backscattering
rad. corrections
Sum
0.3 %
0.1 %
0.3 %
0.0 %
0.1 %
0.1 %
0.45 %
0.5 %
0.25 %
0.26 %
0.1 %
0.1 %
-0.22 %
0.26 %
0.05 %
0.09 %
0.2 %
0.09 %
0.26 %
0.1 %
0.25 %
0.02 %
0.17%
0.05 %
0.11 %
0.003 %
0.09 %
0.01 %
0.001 %
0.05 %
2.04 %
0.66 %
0.38 %
0.41 %
-0.24 %
sum
2006 preliminary
2002: result:
A = -0.1189(8)  = -1.2739(19)
2006:
result:
A = -0.1198(5)  = -1.2762(13)
Hartmut Abele, University of Heidelberg
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a bit history:
 from neutron b-decay
-1.19(2), PDG (1960)
-1.25(2), PDG (1975)
-1.261(4), PDG (1990)
-1.2594(38), Gatchina (1997)
Red:
PDG 2006
-1.2660(40), M, ILL (1997)
-1.2740(30), HD, ILL (1997)
-1.2686(47), Gatchina, ILL (2001)
-1.2739(19), HD, ILL (2002)
-1.2762(13), HD, ILL (2006)
Hartmut Abele, University of Heidelberg
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Hartmut Abele, University of Heidelberg
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Why ratio  = gA/ gV from Neutrons?
Processes with the same Feynman-Diagram
Hartmut Abele, University of Heidelberg
Slide from D. Dubbers
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What about the lifetime?
PDG: 885.7 ± 0.7 s
Serebrov et al.: 878.5 ± 0.7 s
Calculate SM Lifetime
t 1
R
5 4
f
m
2
2
2
e c
 V ud G F (1  3 )
2 3 h 7
t = 880.5 ± 1.5 s
- vs 885.7 ± 0.7 s PDG 2006
- vs 878.5 ± 0.7 s Serebrov et al.
Hartmut Abele, University of Heidelberg
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2. Correlation B in neutron b-decay
Neutrino Asymmetry
A
Neutron Spin
Neutron Spin
Electron

Wd~ (1 + B cos ) d

BB
Neutrino
Neutrino
C
Proton
Hartmut Abele, University of Heidelberg
n  p e e
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The Neutrino-Asymmetry B
Systematically clean method: Integration over two hemispheres
• Electron and Proton in same hemisphere
Neutron Spin
Electron
Proton
Bexp
N  N
 
N  N
Bexp
N  N
 
N
 N
‚‘
Neutrino
• Electron and Proton in opposite hemispheres
Neutron Spin
Electron
Neutrino
Proton
Hartmut Abele, University of Heidelberg
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Proton detector
Proton C foil on 25 keV
n-Spin
Hartmut Abele, University of Heidelberg
Scintillator
Proton detection:
• Measure electron energy
• Wait for proton
• Convert proton into
electron signal
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Proton “electron” spectrum
J. of
Reich
HartmutDissertation
Abele, University
Heidelberg
Dissertation: J. Reich
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Result: Asymmetry B
Thesis: M. Schumann 9 May 2007
• only experiment that measures B
in the same hemisphere
 result is virtually independent
from detector calibration
• result limited by statistics and error
in beam position relative to magn.
field ( magnetic mirror effect)
Background
Bn Displacement
Our Result:
B = 0.9802(50)
New mean Value:
Bmean = 0.9807(30)
Hartmut Abele, University of Heidelberg
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Corrections and Errors: Asymmetry B
Detector 1
Detector 2
Corr. [%] Error [%] Corr. [%] Error [%]
Polarization
+0.3
0.1
+0.3
0.1
Flipper-Efficiency
0.1
0.1
Statistics
1.22
0.36
Coincidence Measurement
0.29
0.07
0.18
0.04
Background
0.10
0.08
Detector
0.02
0.02
Systematics
Mirror Effect
Displacement
+0.44
0.10
0.05
0.32
+0.44
+0.10
0.05
0.32
Other
0.13
0.07
0.13
0.07
.
Other Coefficients
Sum
0.07
+0.22
Hartmut Abele, University of Heidelberg
1.28
0.07
+0.53
0.52
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2. Correlation C in neutron b-decay
A
Electron
C
Neutron Spin
Neutron Spin

Wd~ (1 + C cos ) d

C
Proton
Proton
Hartmut Abele, University of Heidelberg
n  p e e
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Proton Asymmetry C
Dissertation M. Schumann, 2007
Neutron Spin
• proton emission w.r.t. neutron spin:
(coincidence measurement with electrons)
N↑,
N↓
• use electron spectra and
integrate over electron energy E
Proton
Electron
Neutrino
• define ProtonAsymmetry
• Problem: Energy threshold for electron detection
• PERKEO II (2004): C = 0.238(11)
Hartmut Abele, University of Heidelberg
PhD M. Kreuz, J. Res. NIST. 110 (2005)
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Proton Asymmetry C, Results
Thesis: M.Schumann 9 May 2007
Our Result:
Q
Q++
proton in
spin direction
proton against
spin direction
Q+
Q+
C = 0.2377(25)
• first precision measurement
• error dominated by
extrapolation and
detector calibration
• C is better known than
e correlation a
• agrees with SM value:
1) One-parameter fit
2) Extrapolation
3) Integration
Hartmut Abele, University of Heidelberg
CSM = 0.2392(4)
• new SM Tests possible:
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The future
Hartmut Abele, University of Heidelberg
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2002
2002
2006
2006
correction uncertainty correction uncertainty
polarization
flipper efficiency
1.1 %
0.3 %
Statistical error
background
detector function
edge effect
time resolution
mirror effect
backscattering
rad. corrections
Sum
0.3 %
0.1 %
0.3 %
0.0 %
0.45 %
0.5 %
0.25 %
0.1 %
0.1 %
0.26 %
0.1 %
0.1 %
-0.22 %
0.26 %
0.05 %
0.09 %
0.2 %
0.09 %
0.26 %
0.1 %
0.25 %
0.02 %
0.17%
0.05 %
0.11 %
0.003 %
0.09 %
0.01 %
0.001 %
0.05 %
2.04 %
0.66 %
0.38 %
0.41 %
-0.24 %
um
Aim: Spectra and angular distributions distortion-free on the
level of 10-4, 10x better than achieved today
Hartmut Abele, University of Heidelberg
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n-velocity selector
n-polarizer
n-spin flipper
A clean,
bright and
versatile source of
neutron decay products:
n-guide
n-chopper
gap + dump
Perc
n-guide: white, continuous
n-beam
n-guide + solenoid: field B0
polarized, monochromatic
n-pulse
n + γ-beam stop
solenoid, field B1
solenoid, field B2
p+ + e− window-frame
p+ + e− beam
Hartmut Abele, University of Heidelberg
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Expected count rates
Cont. unpol:
After mag. Barrier:
nβ 
Is 
L
 0t
I n  3.6  10 6 I n  1.4  10 6 s 1 .
1 4 x0 y 0 B0
4 1
n

0
.
17
n

6

10
s ,
β
β
2
2 b
2B1
Polarized to 98%:
Tn·Is=1.2104s−1.
Pulsed:
I s' 
Pulsed polarized 99.7%
Hartmut Abele, University of Heidelberg
1 I n '  0 L' L'
I s  0.08 I s  5  10 3 s 1 .
9 I n  2 L L' z 2
Tn'Is'=300s−1.
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SOURCE OF ERROR
non-uniform n-beam
other edge effects on e/p-window
COMMENT
for ΔΦ/Φ = 10 % over 1 cm width
for worst case at max. energy
magn. mirror effect, contin's nbeam
magn. mirror effect, pulsed nbeam
SIZE OF
CORRECT.
SIZE OF
ERROR:
2.5·10−4
5·10−5
4·10−4
1·10−4
1.4·10−2
2·10−4
for ΔB/B = 10 % over 8 m length
5·10−5
<10−5
non-adiabatic e/p-transport
5·10−5
5·10−5
background from n-guide
2∙10−3
1·10−4
2·10−4
1·10−5
backscattering off e/p-window
2·10−5
1·10−5
backscattering off e/p-beam
dump
5∙10−5
backscatt. off plastic scintillator
2∙10−3
background from n-beam stop
}is separately measurable
1∙10−5
~ same with active e/p-beam
dump
}for worst case
neutron polarisation
present status
4·10−4
−
1·10−4
3·10−3
Dubbers,
Baessler,
Märkisch, Schumann, Soldner, Zimmer, H.A.
Hartmut Abele,
University
of Heidelberg
1·10−3
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