Transcript Particle Physics with Neutrons

Neutron Decay
Correlation Experiments
Hartmut Abele
Knoxville, 8 June 2006
Neutron Beta Decay
W ( p )dp 
1
2 3 7c
2
2
2
2
2
G
V
(1

3

)

p
(
E

E
)
dp
F
ud
0
3
Detector
J
Neutron Spin
Electron
A
Electron
Neutron Spin
W(J)={1+v/cPAcos(J)}
Hartmut Abele, University of Heidelberg
Detector2
Coefficient A
W(J)={1+v/cPAcos(J)}

N 
Neutron Spin
J
Electron
A
Electron
Neutron Spin
2 2

0
v
(1

0 c P A cos J) sin J dJd
Coefficient A and lifetime t
determine Vud and 

Aexp


N N
 
N  N
Aexp

N N
 
N  N
A  2
 (  1)
N : electron spectrum w i thspi n fli pper off
N : electron spectrum w i thspi n fli pper on
Aexp
v
 A Pf
c
Vud
2
1  3
2
= gA/gV
4908 2 sec

t  (1  32 )
No coincidences !
Hartmut Abele, University of Heidelberg
3
For a correlation coefficient A
measurements, we need …
Neutrons
a Polarizer
a Spin Flipper
an Analyzer
a Spectrometer
Hartmut Abele, University of Heidelberg
4
Correlation measurements in -decay
Neutron Spin
A
a
Electron
n  p e e
B
D
R
C
Proton
N
Neutrino
Observables in neutron decay:
Lifetime t
Spin
Momenta of decay particles
Hartmut Abele, University of Heidelberg
5
Parameters and Observables
Observables
SM Parameters
Strength: GF
Quark mixing: Vud
Ratio:  = gA/gV
Lifetime t
Correlation A
Correlation fBm c
t  V G (1  3 )
2 h
Correlation C
Correlation a
 (   1)
A  2
Correlation
1  3 D
Correlation R
N N

Beta ASpectrum
N N
Proton Spectrum
v
Polarized
Aexp  A Spectra
Pf
c
Beta Helicity
A
Neutron Spin
Electron
C
R
1
B
2
ud
Neutrino
2
W ( p )dp 
Proton
2
c
3
7




G F V ud (1  3 )  p (E 0  E ) dp
2
3 7
3
2
R
5 4
f
m
2
2
2
e c
 V ud G F (1  3 )
2 3 h 7
1
e
F
exp
t 1
5 4
2
Hartmut Abele, University of Heidelberg
2
2
2
2
6
the Neutron
3-quark System: udd
Beta-decay d  u e
Flux 1.2 x 1015 cm-2 s-1
cold neutrons
ultra cold neutrons
Hartmut Abele, University of Heidelberg
7
Hot topic questions beyond the SM
What do we learn from
Vud and quark mixing?
What is the origin of Pviolation?
Additional forces
Number of quark
generations
Neutrino helicity
Search for RHC: Wmass and mixing 
T-violation?
CP-violation
Hartmut Abele, University of Heidelberg
8
Neutrons at the SNS
Hartmut Abele, University of Heidelberg
9
Neutron Production at the ILL
Hartmut Abele, University of Heidelberg
10
Gravitation and Bound Quantum States
Particle Physics: SM Tests
3D Neutron Tomography
Hartmut Abele, University of Heidelberg
11
Neutron Production
Hartmut Abele, University of Heidelberg
12
1.1 A Measurement of Correlation A
• A new beam: decay rate 1 MHz/m
The ‘ballistic’ super-mirror cold-neutron
guide H113
H. Haese et al., Nucl. Instr. Meth. A485, 453
(2002)
• New Polarizers (TU Munich, ILL, HD)
• New Geometry for Beam polarization
A perfectly polarized neutron beam
•Signal to Background > 1000 : 1
Hartmut Abele, University of Heidelberg
13
M. Schumann 2006
The Experimental Setup at PF1B
Hartmut Abele, University of Heidelberg
14
1.2 Tools
Hartmut Abele, University of Heidelberg
15
UF
Polarizer
100 neV
Spin up: reflected
Spin down: absorbed
x
Coherent nuclear (strong) and electronic (magnetic) scattering
Scattering probability:
resulting polarization:
W   a nucl  a m ag
P 
Hartmut Abele, University of Heidelberg
2
W  W 
 1 a n ucl  a m a g
W  W 
16
T. Soldner, A. Petoukhov, V. Nesvizhevsky, M. Kreuz
Hartmut Abele, University of Heidelberg
17
The new Polarizer
Munich, ILL, HD
A new geometry for Beam
polarization
A perfectly polarized neutron
beam
100 %
96 %
94 %
Status 2002
90 %
100 %
98 %
96 %
95 %
T. Soldner, A. Petoukhov, V. Nesvizhevsky, M. Kreuz
Hartmut Abele, University of Heidelberg
Status 2004
18
Tools
Fermipotential:
UF
100 neV
- Matter 100 neV
Neutron guides
Wavelength filter
Polarizer/Analyzer
UCN
x

Nickel
d
Titan
Nickel
Titan
- perfect mirror
- neutron bottles
2d sin=n
Substrat (Glas)
Hartmut Abele, University of Heidelberg
19
The new Polarizer
Munich, ILL, HD
A new geometry for Beam
polarization
A perfectly polarized neutron
beam
100 %
96 %
94 %
Status 2002
90 %
100 %
98 %
96 %
95 %
Hartmut Abele, University of Heidelberg
Status 2004
20
Rf Spin flipper
Lab frame
Rotating frame
Rotating frame
Hartmut Abele, University of Heidelberg
21
The Instrument
Hartmut Abele, University of Heidelberg
22
1.3 Coefficient A: Spectrometer Perkeo II
precise electron spectroscopy
Neutron Spin
Electron
to beamstop
A
Electron
Neutron Spin
up:
Aexp
Hartmut Abele, University of Heidelberg
down:
N  N
 
N  N
Aexp
N  N
 
N  N
23
oben:
Spectrometer Perkeo II
Aexp
N  N
 
N  N
unten:
Aexp
N  N
 
N  N
precise electron spectroscopy
Principle:
2x2- Detection
two hemispheres
backscattering suppression
low background
strong beam PF1:
- count ratesystematic
A exp  A
v
 (   1)
P f A  2
c
1  3 2
zum beamstop
= gA/gV
Hartmut Abele, University of Heidelberg
24
Results
Spectra
Dissertation D. Mund, 2006
Hartmut Abele, University of Heidelberg
25
Result
Asymmetry A
Hartmut Abele, University of Heidelberg
Dissertation D. Mund, 2006
26
Beamrelated Background
Collimation system
< 0.15 s-1
ElectronSpectrum
Beamline BG
Det. 0
Det. 1
Fitregion
Hartmut Abele, University of Heidelberg
27
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 %
0.1 %
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 %
0.33 %
-0.24 %
sum
2006 preliminary
2002: result:
A = -0.1189(8)  = -1.2739(19)
2006:
result:
A = -0.11948(40)  = -1.2754(11)
Hartmut Abele, University of Heidelberg
28
Collaboration PERKEOII 1995 - 2006
Universität Heidelberg
Stefan Baeßler, C. Raven, T. Müller, C. Metz,
M. Astruc Hoffmann, Uta Peschke, Jürgen
Reich, Bernhard Brand, Michael Kreuz,
Ulrich Mayer Daniela Mund, Christian Plonka,
Christian Vogel, Bastian Märkisch, Markus
Brehm, Jochen Krempel, Marc Deissenroth,
Marc Schumann, Alexander Kaplan, Daniel
Wilkin, Dirk Dubbers, H.A.
ILL Grenoble
J. Last, U. Mayerhofer, O. Zimmer,
V. Nesvizhevsky, T. Soldner, A. Petoukhov
FZK
F. Glück
U. Mainz
S. Baeßler
Hartmut Abele, University of Heidelberg
29
Hartmut Abele, University of Heidelberg
30
Recommended value for lambda
 = -1.27500.0009
Hartmut Abele, University of Heidelberg
31
1.4 A and 
A as a function of gA and gV
Time reversal invariance, phase 180°
ve = c, v = c,
 see Lecture at Black Board
Hartmut Abele, University of Heidelberg
32
Hartmut Abele, University of Heidelberg
33
Thesis Doehner 1991
Hartmut Abele, University of Heidelberg
34
Hartmut Abele, University of Heidelberg
35
Hartmut Abele, University of Heidelberg
36
PROCESSES WITH SAME FEYNMAN DIAGRAM:
• Solar cycle
= gA/gV
• Neutron star formation
p p  D e+ e
p p e  D e
…
p e n e
•Primordial element formation n e+  p  e'
p e n  e
n  p e e'
•Neutrino detectors
p  e'  n e+
•Neutrino forward-scattering  e p  e+ n etc.
•W, Z-production
Hartmut Abele, University of Heidelberg
p p'  W  e  e' etc.
37