Display the Report for S1070, report 200512S

Experiment: S1070

Upgrade of 38mK Β-ν correlation

by the TRINAT group

Active (Stage 2)
Spokespersons:
J.A. Behr (TRIUMF)

Original Proposal for EEC meeting 200512S

Table of Contents

Detailed Information

Proposal/Report S1070_proposal.pdf (625.95 kB)

Beam Shift Summary

12-hr ShiftsBeam Line / channelPolarized Primary BeamPriority
New Beam Requests
 30 BL2A/ISAC/TiC No
Committee Recommendations
 30 No H

The Committee heard a discussion of the accomplishments and future plans for the 38mK beta-neutrino correlation experiment. The presentation was mostly an update. The most recently published value of the neutrino correlation by this group is comparable to the best available. The proponents argue that with achievable improvements they will be able to significantly increase the precision on a) the electron-neutrino correlation coefficient, and b) the Fierz interference term. The major instrumental improvement is larger multi-channel plate detectors. They also intend to adopt the technique of detecting shake-off electrons for a start signal to replace the present positron signal now used in the experiment. This method increases the data rate and reduces biases arising from detecting positrons. Other improvements are attributed to better characterization of known systematic uncertainties. The Committee was pleased to hear about the accomplishments of this part of the TRINAT program and continues to regard this as a high priority program for TRIUMF. The Committee will be interested in hearing about the progress on this experiment as soon as it is appropriate.


Membership

J.A. Behr TRIUMF Research Scientist 100 % Spokesperson

Basic Information

Date Submitted
2005-11-29 11:07:40
Date Experiment Ready
0000-00-00
Projected Completion Date
0000-00-00
Summary *

The TRIUMF Neutral atom trap collaboration has pioneered the direct measurement of Β+-ν angular distributions by measuring the momentum of the few 100-eV energy recoiling nucleus in coincidence with the positron.

We have published the best limits on general scalar interactions coupling to the first generation of particles [A. Gorelov et al. Phys. Rev. Lett. 94 142501 (2005).] We propose to improve the overall accuracy of this Β-ν correlation experiment by a factor of 3. We also would extend it to lower Β energy to improve sensitivity to the scalar-vector Fierz interference term and hence gain linear sensitivity to certain types of scalars, reaching accuracy directly competitive with the Q-value dependence of 0+ → 0+ ft values.

Although there are many direct and indirect constraints on scalar interactions, there is little theoretical guidance about scalar interactions and so direct experiments with general sensitivity are still of great interest. The theoretical interpretation of the Β-ν correlation in our case is independent of nuclear structure calculations. The radiative corrections (mostly real γ emission via bremsstrahlung) make an 0.2% correction and are reliable to an order of magnitude better than needed.

ISAC has demonstrated 38mK yields 5x greater than those for the published experi- ment, and we have also improved our collection efficiency by 3x by adding another ring laser. Most of our systematic errors are given by statistically limited ts of different aspects of the data in situ. We have the best experiment and have good ideas on what to fix and upgrade to make it considerably better.

Plain Text Summary *
Primary Beam Line
ISAC TRINAT
Primary Beam and Target
500 MeV protons, TiC target, 45 μA
Secondary Channel
ISAC LEBT
Secondary Beam
38mK 5x107/sec
TRIUMF Support (Resources Needed)
Continued support of existing TRINAT lab at ISAC
Other Funding
NSERC TRINAT project grant (J.A. Behr et al): present support through April 2006. Continuing support reapplied for.
Safety Issues

Radiation: ISAC target and LEBT operation to TRINAT clean room in ISAC. J.A. Behr safety o±cer. 38K g.s. contaminant 2.17 MeV ° creates local safety hazard controlled by personnel access, which we have demonstrated in the past. The 38Ar daughter is stable.

Procedures for safety of the laser systems preclude access to the TRINAT clean room at ISAC. J.A. Behr laser safety o±cer.

Proposals and Progress Reports

200712S
200512S (Original Proposal)