Display the Experiment Proposals for S1188

Experiment: S1188

Measurement of spin-polarized observables in the β+ decay of 37K

by the TRINAT group

Active (Stage 2)
Spokespersons:
D.G. Melconian (Texas A&M University)

Original Proposal for EEC meeting 200807S

Table of Contents

Detailed Information

Complete/Merged PDF S1188_200807S_merged.pdf
Form data only S1188_200807S.pdf
Detailed Statement EEC2008.pdf (623.58 kB)

Beam Shift Summary

12-hr ShiftsBeam Line / channelPriority
New Beam Requests
 30 TRINAT
To measure the neutrino asymmetry parameter to 0.3% and at the same time make a measurement of the Rslow observable
10 TRINAT
To measure the beta asymmetry parameter in 37K to 0.3% and add statistics to an Rslow measurement
Committee Recommendations
 40 Trinat H

There is tremendous potential in a more precise measurement of the asymmetry parameters Aβ, Bν, and Rslow from 37K decay. At the readily achievable 0.5% level, the 37K decay is very competitive with neutron decay in setting limits on left/right manifestly symmetric models, and provides an important independent validation of the limits. At the 0.1% level, 37K decay will set a much more stringent limit than neutron decay. The goal of S1188 is to achieve a measurement of all parameters to the 0.3% level. This will not only provide an important constraint to searches to physics beyond the Standard Model, but will also elucidate the dominant sources of uncertainty that must be overcome to achieve an even higher precision.

The committee considers this proposal as having the potential to generate a very significant result. While the limits on the asymmetry parameters of 0.3% with the current proposal, and even a future goal of 0.1%, will not provide a more stringent constraint on right-handed currents than that currently set from muon decay, it is very important to obtain these data in order to constrain supersymmetric extensions of the Standard Model that, for large areas of parameter space, allow for differences in the asymmetry parameters between the quark generations. The committee recommends that the authors investigate the impacts of their measurements on the parameter spaces of Standard Model extensions, which will be important in consideration of this programme beyond the current proposal.


Membership

D.G. Melconian Texas A&M University Assistant Professor 60 % Spokesperson
A. Gorelov Simon Fraser University Student (PhD) 100 %  
J.A. Behr TRIUMF Research Scientist 100 %  
K.P. Jackson TRIUMF Research Scientist 30 %  
M.R. Pearson TRIUMF Research Scientist 30 %  
D. Ashery Tel Aviv University Professor 15 %  

Basic Information

Date Submitted
2008-06-09 22:02:20
Date Experiment Ready
2009-05-01
Summary *

We propose to measure spin-polarized observables in the beta decay of 37K. In particular, we are interested in the beta and neutrino asymmetries as well as an observable particular to our geometry we have termed Rslow. These observables are all sensitive to new physics (e.g. right-handed currents, second-class currents, the value of Vud, time-violating interactions and tensor interactions).

TRINAT, the neutral atom trap facility at ISAC/TRIUMF, is well suited for such precision beta decay studies. TRINAT has developed a mature program that has yielded one of the most stringent limits on scalar currents in the weak interaction and set limits on possible heavy, sterile neutrinos. We have already proven the ability to highly polarize (>95%) a sample of laser-cooled radioactive atoms and measure the neutrino asymmetry in 37K, however the precision of this pioneering experiment was not sufficient to test the standard model; this first-ever polarized experiment of laser-cooled atoms did, however, allow us to identify our dominant systematics and we now know how to reduce all of them. Our estimates indicate that a 0.3-0.5% measurement of three spin-polarized observables is possible within a modest amount of beam time (40 shifts). Such an experiment alone would complement other searches for new physics, but to be truly competitive our ultimate goal is to measure these observables to 0.1%. After the initial measurement to 0.5%, we would re-evaluate systematics and then proceed to the 0.1% measurement. Once realized, these results would be more sensitive to new physics than the present world average of neutron beta decay, and would have a significant impact on the sensitivity of the world average from nuclear beta decay.

Plain Text Summary *
The spin-polarized observables in the beta decay of 37K can be a sensitive probe of new physics if measured precisely. The TRINAT facility coupled to the exotic beams produced by ISAC/TRIUMF is well-suited for such measurements. The short-lived atoms to be studied are: cooled and localized by the neutral atom trap; highly polarized; and both the recoil and emitted positron are cleanly detected. Measurement of the beta and neutrino asymmetries to 0.1% will be competitive with other searches for new physics.
Primary Beam Line
ISAC 2A
ISAC Facilities
ISAC Facility
TRINAT
Secondary Beam
Isotope(s)
37K
Energy
30
Energy Units
keV
Intensity Requested (pps)
7e7(pps)
Minimum Intensity (pps)
2e7(pps)
Maximum Intensity (pps)
1e12(pps)
Experiment Support
Beam Diagnostics Required
  • No special beam diagnostics are required.
Signals for Beam Tuning
  • TRINAT has diagnostics which have routinely been used to help tune the beam from ISAC.
DAQ Support
(Summary of Requirements)
  • The current DAQ system is expected to be adequate, however small amounts of consultation with DAQ group will be made as necessary.
TRIUMF Support (Resources Needed)
  • Continued infrastructure support for the TRINAT lab, however no special support for this experiment is requested
NSERC
  • TRINAT project grant
Other Funding
  • Start-up funds for D. Melconian from the Cyclotron Institue and Texas A&M University
Safety Issues
  • Radiation: typical ISAC target and LEBT operation to TRINAT clean room in ISAC
  • Procedures for safety of the laser systems preclude general access to the TRINAT clean room.

Proposals and Progress Reports

200807S (Original Proposal)