Schleching 2008 4.1 Präzisionsphysik mit Neutron en / 4. Experimente diesseit s SM Primordial element formation n + e + ↔ p + ν' e σ ν ~ 1/τ ( 2 H, 3 He, 4 He, 7 Li) p + e − ↔ n + ν e σ ν ~ 1/τ n ↔ p + e − + ν' e τ Solar cycle p + p ↔ 2 H + e + + ν e p + p + e − ↔ 2 H + ν e etc. ~ (g A /g V ) 5 Neutron star formation p + e − ↔ n + ν e Pion decay π − ↔ π 0 + e − + ν' e Neutrino detectors ν' e + p ↔ e + + n Neutrino forward scattering ν e + n ↔ e − + p etc. W and Z production u' + d ↔ W − e − + ν' e etc. Neutron decay data are useful u e − W d ν e e − ν e W d u' d ν e W u e −
Neutron decay data are useful. d ν e W u e −. u e − W d ν e. e − ν e W d u'. Many processes have the same Feynman diagram as neutron decay: Primordial element formation n + e + ↔ p + ν ' e σ ν ~ 1/ τ - PowerPoint PPT Presentation
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Schleching 2008 4.1Präzisionsphysik mit Neutronen / 4. Experimente diesseits SM
Many processes have the same Feynman diagram as neutron decay:
Primordial element formation n + e+ ↔ p + ν'e σν ~ 1/τ
(2H, 3He, 4He, 7Li) p + e− ↔ n + νe σν ~ 1/τ
n ↔ p + e− + ν'e τ
Solar cycle p + p ↔ 2H + e+ + νe
p + p + e− ↔ 2H + νe etc. ~ (gA/gV)5
Neutron star formation p + e− ↔ n + νe
Pion decay π− ↔ π0 + e− + ν'e
Neutrino detectors ν'e + p ↔ e+ + n
Neutrino forward scattering νe + n ↔ e− + p etc.
W and Z production u' + d ↔ W− e− + ν'e etc.
… precision data of weak interaction parameters
today only from neutron decay
Neutron decay data are useful
u e−
W
d νe
e− νe
W
d u'
d νe
W
u e−
Schleching 2008 4.2Präzisionsphysik mit Neutronen / 4. Experimente diesseits SM
calculated gains in neutron count rates
ILL-Millenium program
Mean gain in ILL total efficiency
0
2
4
6
8
10
12
14
16
18
19
99
20
01
20
03
20
05
20
07
20
09
Year
Instr.+GuideRenewal
Instr. RenewalOnly
Schleching 2008 4.3Präzisionsphysik mit Neutronen / 4. Experimente diesseits SM
2001 S-DH GmbH: Neutron optics, H. Häse
2006 CASCADE GmbH : large fast n-detectors, M. Klein, C. Schmidt
Schleching 2008 4.4Präzisionsphysik mit Neutronen / 4. Experimente diesseits SM
Temperature kT = 10+19 GeV Planck scale
10+16 GeV Grand Unification Inflation ... ... wenn H = å/a ≈ const. Chiral phase transition Nucleon freeze out Electroweak transition Nuclear freeze out Atomic freeze out
Galactic freeze out 10-11 GeV (T = 2.726 K) Big Bang 10-43 s 10-35 s 10-12 s 1 s 105 y 109 y today
Time
…
t
History of the universe: a succession of phase transitions
TP NP AP FKP
Schleching 2008 4.5Präzisionsphysik mit Neutronen / 4. Experimente diesseits SM
versatile: vary width and divergence of emerging p+, e− beam
without change of spectral properties
collect charged decay products from within a long piece of cold n-guide:
n-guide = source of neutron decay products:
"Proton-Electron Radiation Channel" PERC
neutron puls in long piece of n-guide
B ~Tesla e−
p+
Schleching 2008 4.14Präzisionsphysik mit Neutronen / 4. Experimente diesseits SM
example for setup:
example: B0=2T, B1=8T, B2=½T:
count rates:6104 s−1 for a continuous unpolarized n-beam; 1104 s−1 for a continuous beam polarized to 98%; 3103 s−1 for a pulsed unpolarized beam;3102 s−1 for a pulsed beam polarized to 99.5%.
beam time for ~10−4 statistical error:½ h for continuous unpolarized, 3 h for continuous polarized,10 h for pulsed unpolarized, 4 d for pulsed polarized
10m
ILL user
Schleching 2008 4.15Präzisionsphysik mit Neutronen / 4. Experimente diesseits SM
Error budget of PERC (not all measurements sensitive to all errors) correction error
orifice: in units of 10−4
1. non-uniform neutron beam profile over orifice 0.6 0.2
2. finite thickness of orifice eliminated
3. electron escape from orifice 1 0.2
solid angle of p+, e− emission:
4. non-uniformity of B0-field 1 0.3
5. non-adiabatic variation of B1-field; adiabatic decoupling from B2-field 0.5 0.5 (M-C- req.)
background:
6. from neutron guide 4 1
7. from n-beam shutter, pulsed neutron beam non-existent
from n-beam shutter, continuous neutron beam 1 1 (exp. study req.)
8. from n-beam stop, pulsed neutron beam non-existent
from n-beam stop, continuous neutron beam 2 1
e−/p+ backscattering:
9. from beam window 1 0.2
10. from electron/proton beam dump 2 0.4
11. from electron/proton detector (user's responsibility) 6 1
neutron polarization:
12. polarisation measurement 5 5
13. depolarisation in non-magnetic supermirror guide ≤5
At present (for β-asymmetry A, total, D. Mund (2005)): present: 34 present: 39
Schleching 2008 4.16Präzisionsphysik mit Neutronen / 4. Experimente diesseits SM