The Neutron Alphabet Exploring the properties of fundamental interactions with cold neutrons Hartmut...

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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

Experimental Groups, Neutron -DecayNew experiments are greatly profiting from new sources & techniques

Talks at NIST workshop from different groups in 2004:

Facilities

Nico, Snow, Annu Rev Nucl Part Sci 55 (2005) 55

Facilities

Nico, Snow, Annu Rev Nucl Part Sci 55 (2005) 55

Nuclear and Particle Physics

Neutrograph, Radio- and Tomography station

The PERKEO II Setup @ ILL1. Polarizer

2. Spin Flipper

3. Spectrometer 4. Beam Stop

M. Schumann 2006M. Schumann 2006

The new Polarizer: 99.7 % EfficiencyKreuz, Soldner, Pekoutov, Nesvizhevsky, NIM 2006

ILL, HDA new geometry for Beam polarization Towards a perfectly polarized neutron beam

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

nucl magW a a

Rf Spin flipper: 100% efficiencyT. Soldner & A. Petoukhov

Lab frame

Rotating frame

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

Experiments

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

PERKEO III

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

V p f k k if k k nf k

Ffi 5 5

GT | (1 ) | ( (1 ) )

2udV p n e

Talk Marc Schumann at ILL

a Spect, Univ. MZ/TUM

Proton spectroscopy

aSPECT is a retardation spectrometer for protons of free neutron decay

aSPECT

First impression

PNPI Experiment

Surface barrier

detector

D-Coefficient

Electron and neutrino momenta from electron energycose from proton momentum and electron energy using4T 1TTOF between electron and proton

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

Results: A

ElectronNeutron Spin

Results PERKEO II(2006)

Spectra Dissertation D. Mund, 2006

Result for A

Dissertation D. Mund, 2006

Beamrelated Background

Collimation system < 0.15 s-1

Det. 0

Det. 1

Fitregion

Electron-Spectrum

Beamline BG

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)

-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

Why ratio = gA/ gV from Neutrons?

Processes with the same Feynman-Diagram

Slide from D. Dubbers

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

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

• 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

NNBexp

Systematically clean method: Integration over two hemispheres

‚‘‚‘

Proton detector

C foil on 25 keV ScintillatorProton

Proton detection:• Measure electron energy• Wait for proton• Convert proton into electron signal

n-Spin

Proton “electron” spectrum

Dissertation: J. Reich Dissertation J. Reich

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)

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

2. Correlation C in neutron -decay

n n p e p e ee

Proton

Neutron Spin

WdWd~ (1 + ~ (1 + CC cos cos ) )

Electron

Proton

Neutron Spin

• 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

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:

C = 0.2377(25)

CSM = 0.2392(4)

The future

Aim: Spectra and angular distributions distortion-free on the level of 10-4, 10x better than achieved today

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:

..I.IL

0β s10411063

Expected count ratesCont. unpol:

After mag. Barrier:

Polarized to 98%:

Pulsed:

Pulsed polarized 99.7%

yxI 14

00s s106170

Tn·Is=1.2104s−1.

.I.Iz'L

'I'I 13

ns s105080

Tn'Is'=300s−1.

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.

The Neutron Alphabet Exploring the properties of fundamental interactions with cold neutrons Hartmut...

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