the neutron alphabet exploring the properties of fundamental interactions with cold neutrons
DESCRIPTION
The Neutron Alphabet Exploring the properties of fundamental interactions with cold neutrons. Hartmut Abele. The Neutron Alphabet and Symmetries. A: P-odd B: P-odd C: P-odd D: T-odd a N R: T-odd. A. Neutron Spin. . Electron. B. Neutrino. C. Proton. - PowerPoint PPT PresentationTRANSCRIPT
The Neutron Alphabet Exploring the properties offundamental interactions with cold neutrons
Hartmut Abele
Hartmut Abele, University of Heidelberg 2
The Neutron Alphabet and Symmetries
A: P-oddB: P-oddC: P-oddD: T-oddaNR: T-odd
Electron
Proton
Neutrino
Neutron Spin
A
B
C
Hartmut Abele, University of Heidelberg 3
Experimental Groups, Neutron -DecayNew experiments are greatly profiting from new sources & techniques
Talks at NIST workshop from different groups in 2004:
Hartmut Abele, University of Heidelberg 4
Facilities
Nico, Snow, Annu Rev Nucl Part Sci 55 (2005) 55
2.0
Hartmut Abele, University of Heidelberg 5
Facilities
Nico, Snow, Annu Rev Nucl Part Sci 55 (2005) 55
Hartmut Abele, University of Heidelberg 6
Nuclear and Particle Physics
Neutrograph, Radio- and Tomography station
Hartmut Abele, University of Heidelberg 7
The PERKEO II Setup @ ILL1. Polarizer
2. Spin Flipper
3. Spectrometer 4. Beam Stop
M. Schumann 2006M. Schumann 2006
Hartmut Abele, University of Heidelberg 8
The new Polarizer: 99.7 % EfficiencyKreuz, Soldner, Pekoutov, Nesvizhevsky, NIM 2006
ILL, HDA new geometry for Beam polarization Towards a perfectly polarized neutron beam
2
nucl magW a a Status 2002
Status 2004
98 %98 %
100 %100 %
96 %96 %
100 %100 %
90 %90 %
95 %95 %
94 %94 %
96 %96 %
Spin up: reflectedSpin down: absorbed
Coherent nuclear (strong) and electronic (magnetic) scattering
1W W
PW W
2
nucl magW a a
Hartmut Abele, University of Heidelberg 9
Rf Spin flipper: 100% efficiencyT. Soldner & A. Petoukhov
Lab frame
Rotating frame
Rotating frame
Hartmut Abele, University of Heidelberg 10
Cold NeutronsFor Correlation Coefficient A Measurements…
High Flux: = 2 x 1010 cm-2s-1
Decay rate of 1 MHz / meter / sec
Count rate: 106 s-1
Polarized to 98%: 2.5 x 105 s-1 Polarized to 99.7%: 1.4 x 105 s-1
Pulsed/unpulsed
Spectrometer
Hartmut Abele, University of Heidelberg 11
Experiments
Hartmut Abele, University of Heidelberg 12
Characteristics of Experiments
Using Magnetic Fields
PERKEO III
Hartmut Abele, University of Heidelberg 13B. Maerkisch, D. Dubbers, H.A. et al.B. Maerkisch, D. Dubbers, H.A. et al.
Small systematic errors - background
- edge effect
- mirror effect
PERKEO III20 October 2006 – 11 April 2007
to beamstop
Hartmut Abele, University of Heidelberg 14
PERKEO III
Hartmut Abele, University of Heidelberg 15
Hartmut Abele, University of Heidelberg 16
Hartmut Abele, University of Heidelberg 17
Hartmut Abele, University of Heidelberg 18
Hartmut Abele, University of Heidelberg 19
Aim: Weak Magnetism form factor f2
Neutron Decay Transition Matrix:
Electron Asymmetry:
f2 Weak Magnetism Form Factor(SM prediction)
2 % additional Edependence of A
PERKEO III can deliver the necessary statistics!
2 21 3
22[ ( ) ( ) ]|2
( )
p
V p f k k if k k nf k
m
Ffi 5 5
GT | (1 ) | ( (1 ) )
2udV p n e
Talk Marc Schumann at ILL
Hartmut Abele, University of Heidelberg 20
a Spect, Univ. MZ/TUM
Proton spectroscopy
Hartmut Abele, University of Heidelberg 21
aSPECT is a retardation spectrometer for protons of free neutron decay
aSPECT
First impression
Hartmut Abele, University of Heidelberg 22
PNPI Experiment
Hartmut Abele, University of Heidelberg 23
aCORN
Surface barrier
detector
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Hartmut Abele, University of Heidelberg 25
D-Coefficient
emiT
Trine
Hartmut Abele, University of Heidelberg 26
Nab
Electron and neutrino momenta from electron energycose from proton momentum and electron energy using4T 1TTOF between electron and proton
Hartmut Abele, University of Heidelberg 27
California Institute of TechnologyR. Carr, B. Filippone, J. Hsiao, R. McKeown, B. Plaster, B. Tipton, J. Yuan
Institute Lau-LangevinP. Geltenbort
Idaho State UniversityR. Rios, E. Tatar
Los Alamos National LaboratoryJ. 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/TUNLH. O. Back, L. Broussard, A. T. Holley, R. K. Jain, R. W. Pattie, K. Sabourov, A. R.
Young (co-spokesperson), Y.-P. XuPetersburg Nuclear Physics Institute
A. Aldushenkov, A. Kharitonov, I. Krasnoshekova, M. Lasakov, A. P. Serebrov, A. Vasiliev
Tohoku UniversityS. Kitagaki
University of KyotoM. Hino, T. Kawai, M. Utsuro
University of WashingtonA. Garcia, S. Hoedl, D. Melconian, A. Sallaska, S. Sjue
University of WinnipegJ. Martin
Virginia Polytechnic Institute and State UniversityR. Mammei, M. Pitt, R. B. Vogelaar
UCNA Collaboration
Hartmut Abele, University of Heidelberg 28
Results: A
ElectronNeutron Spin
A
Hartmut Abele, University of Heidelberg 29
Results PERKEO II(2006)
Spectra Dissertation D. Mund, 2006
Hartmut Abele, University of Heidelberg 30
Result for A
Dissertation D. Mund, 2006
exp
1 v
2 c
N NA
N N
PfA
exp
1 v
2 c
N NA
N N
PfA
2
( 1)2
1 3A
Hartmut Abele, University of Heidelberg 31
Beamrelated Background
Collimation system < 0.15 s-1
Det. 0
Det. 1
Fitregion
Electron-Spectrum
Beamline BG
Hartmut Abele, University of Heidelberg 32
2002 2002 2006 2006 correction uncertainty correction uncertainty polarization 1.1 % 0.3 % 0.3 % 0.1 % flipper efficiency 0.3 % 0.1 % 0.0 % 0.1 % Statistical error 0.45 % 0.26 % background 0.5 % 0.25 % 0.1 % 0.1 % detector function 0.26 % 0.26 % edge effect -0.24 % 0.1 % -0.22 % 0.05 % time resolution 0.25 % mirror effect 0.09 % 0.02 % 0.11 % 0.01 % backscattering 0.2 % 0.17% 0.003 % 0.001 % rad. corrections 0.09 % 0.05 % 0.09 % 0.05 % Sum 2.04 % 0.66 % 0.38 % 0.41 %
sum 2006 preliminary
2002 2002 2006 2006 correction uncertainty correction uncertainty polarization 1.1 % 0.3 % 0.3 % 0.1 % flipper efficiency 0.3 % 0.1 % 0.0 % 0.1 % Statistical error 0.45 % 0.26 % background 0.5 % 0.25 % 0.1 % 0.1 % detector function 0.26 % 0.26 % edge effect -0.24 % 0.1 % -0.22 % 0.05 % time resolution 0.25 % mirror effect 0.09 % 0.02 % 0.11 % 0.01 % backscattering 0.2 % 0.17% 0.003 % 0.001 % rad. corrections 0.09 % 0.05 % 0.09 % 0.05 % Sum 2.04 % 0.66 % 0.38 % 0.41 %
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 33
-1.19(2), PDG (1960)
-1.25(2), PDG (1975)
-1.261(4), PDG (1990)
-1.2594(38), Gatchina (1997)
-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)
a bit history:from neutron -decay
Red: PDG 2006
Hartmut Abele, University of Heidelberg 34
Hartmut Abele, University of Heidelberg 35
Why ratio = gA/ gV from Neutrons?
Processes with the same Feynman-Diagram
Slide from D. Dubbers
Hartmut Abele, University of Heidelberg 36
What about the lifetime?PDG: 885.7 ± 0.7 s
Serebrov et al.: 878.5 ± 0.7 s
Calculate SM Lifetime
= 880.5 ± 1.5 s- vs 885.7 ± 0.7 s PDG 2006
- vs 878.5 ± 0.7 s Serebrov et al.
5 41 2 2 2
3 7(1 3 )2ud
Re
F
fV
mG
ch
Hartmut Abele, University of Heidelberg 37
2. Correlation B in neutron -decay Neutrino Asymmetry
n n p e p e ee
WdWd~ (1 + ~ (1 + BB cos cos ) ) dd
Neutrino
Neutron Spin
BElectron
Proton
Neutrino
Neutron Spin
A
B
C
Hartmut Abele, University of Heidelberg 38
• Electron and Proton in same hemisphere
• Electron and Proton in opposite hemispheres
The Neutrino-Asymmetry B
Electron Proton
Neutron Spin
Neutrino
Electron
Proton
Neutrino
Neutron Spin
NN
NNBexp
NN
NNBexp
Systematically clean method: Integration over two hemispheres
‚‘‚‘
Hartmut Abele, University of Heidelberg 39
Proton detector
C foil on 25 keV ScintillatorProton
Proton detection:• Measure electron energy• Wait for proton• Convert proton into electron signal
Proton detection:• Measure electron energy• Wait for proton• Convert proton into electron signal
n-Spin
Hartmut Abele, University of Heidelberg 40
Proton “electron” spectrum
Dissertation: J. Reich Dissertation J. Reich
Hartmut Abele, University of Heidelberg 41
Our Result:
New mean Value:
Bmean = 0.9807(30)
Result: Asymmetry BThesis: M. Schumann 9 May 2007
Background Bn Displacement
B = 0.9802(50)
• 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)
Hartmut Abele, University of Heidelberg 42
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
+0.440.10
0.050.32
+0.44+0.10
0.050.32
Other 0.13 0.07 0.13 0.07
Other Coefficients 0.07 0.07
Sum +0.22 1.28 +0.53 0.52
Hartmut Abele, University of Heidelberg 43
2. Correlation C in neutron -decay
n n p e p e ee
Proton
Neutron Spin
C
WdWd~ (1 + ~ (1 + CC cos cos ) )
dd
Electron
Proton
Neutron Spin
A
C
Hartmut Abele, University of Heidelberg 44
• proton emission w.r.t. neutron spin: N↑, N↓ (coincidence measurement with electrons)
• use electron spectra and integrate over electron energy E
• define ProtonAsymmetry
• Problem: Energy threshold for electron detection
• PERKEO II (2004): C = 0.238(11) PhD M. Kreuz, J. Res. NIST. 110 (2005)
Proton Asymmetry C
Electron Proton
Neutron Spin
Neutrino
Dissertation M. Schumann, 2007
Hartmut Abele, University of Heidelberg 45
Proton Asymmetry C, ResultsThesis: M.Schumann 9 May 2007
1) One-parameter fit2) Extrapolation3) Integration
proton in spin direction
proton against spin direction
Our Result:
• first precision measurement
• error dominated by extrapolation and detector calibration
• C is better known than e correlation a
• agrees with SM value:
• new SM Tests possible:
Q++
Q+
Q
Q+
C = 0.2377(25)
CSM = 0.2392(4)
Hartmut Abele, University of Heidelberg 46
The future
Hartmut Abele, University of Heidelberg 47
2002 2002 2006 2006 correction uncertainty correction uncertainty polarization 1.1 % 0.3 % 0.3 % 0.1 % flipper efficiency 0.3 % 0.1 % 0.0 % 0.1 % Statistical error 0.45 % 0.26 % background 0.5 % 0.25 % 0.1 % 0.1 % detector function 0.26 % 0.26 % edge effect -0.24 % 0.1 % -0.22 % 0.05 % time resolution 0.25 % mirror effect 0.09 % 0.02 % 0.11 % 0.01 % backscattering 0.2 % 0.17% 0.003 % 0.001 % rad. corrections 0.09 % 0.05 % 0.09 % 0.05 % Sum 2.04 % 0.66 % 0.38 % 0.41 %
sum
2002 2002 2006 2006 correction uncertainty correction uncertainty polarization 1.1 % 0.3 % 0.3 % 0.1 % flipper efficiency 0.3 % 0.1 % 0.0 % 0.1 % Statistical error 0.45 % 0.26 % background 0.5 % 0.25 % 0.1 % 0.1 % detector function 0.26 % 0.26 % edge effect -0.24 % 0.1 % -0.22 % 0.05 % time resolution 0.25 % mirror effect 0.09 % 0.02 % 0.11 % 0.01 % backscattering 0.2 % 0.17% 0.003 % 0.001 % rad. corrections 0.09 % 0.05 % 0.09 % 0.05 % Sum 2.04 % 0.66 % 0.38 % 0.41 %
sum
Aim: Spectra and angular distributions distortion-free on the level of 10-4, 10x better than achieved today
Hartmut Abele, University of Heidelberg 48
n-guide: white, continuous n-beam
n-velocity selectorn-polarizern-spin flipper
n-guiden-choppergap + dump
n-guide + solenoid: field B0
polarized, monochromatic n-pulse
n + γ-beam stopsolenoid, field B1
solenoid, field B2
p+ + e− window-framep+ + e− beam
A clean, bright andversatile source ofneutron decay products:
Perc
Hartmut Abele, University of Heidelberg 49
..I.IL
n 16n
6n
0β s10411063
Expected count ratesCont. unpol:
After mag. Barrier:
Polarized to 98%:
Pulsed:
Pulsed polarized 99.7%
,n.nB
B
b
yxI 14
ββ1
02
00s s106170
2
4
2
1
Tn·Is=1.2104s−1.
.I.Iz'L
'L
L
'L
I
'I'I 13
ss22
0
n
ns s105080
9
1
Tn'Is'=300s−1.
Hartmut Abele, University of Heidelberg 50
SOURCE OF ERROR COMMENT SIZE OF CORRECT.
SIZE OF
ERROR:
non-uniform n-beamfor ΔΦ/Φ = 10 % over 1 cm width
2.5·10−4 5·10−5
other edge effects on e/p-window
for worst case at max. energy4·10−4
1·10−4
magn. mirror effect, contin's n-beam
1.4·10−2
2·10−4
magn. mirror effect, pulsed n-beam
for ΔB/B = 10 % over 8 m length5·10−5
<10−5
non-adiabatic e/p-transport 5·10−5 5·10−5
background from n-guide}is separately measurable
2∙10−3 1·10−4
background from n-beam stop
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
1∙10−5
backscatt. off plastic scintillator
}for worst case
2∙10−3
4·10−4
~ same with active e/p-beam dump
−1·10−4
neutron polarisation present status 3·10−3 1·10−3
Dubbers, Baessler, Märkisch, Schumann, Soldner, Zimmer, H.A.