Jules Deutsch

Scalar interaction limits from the beta-ne correlation of trapped radioactive atoms

We have set limits on contributions of scalar interactions to nuclear beta decay. A magneto-optical trap provides a localized source of atoms suspended in space, so the low-energy recoiling nuclei can freely escape and be detected in coincidence with the beta. This allows reconstruction of the neutrino momentum, and the measurement of the beta-nu correlation, in a more direct fashion than previously possible. The beta-nu correlation parameter of the 0(+)-->0(+) pure Fermi decay of (38)K(m) is a =0.9981+/-0.0030+0.0032 / -0.0037, consistent with the standard model prediction a =1.

A precision measurement of nuclear muon capture on 3He

In this article we report the results of an experiment performed in 1993 at PSI. The goal was to determine the absolute rate of nuclear muon capture by3He. In the experiment we used a new technique recently developed at Gatchina. As a preliminary result from this experiment we obtainedλc=(1496±3(stat)-3(syst)) s−1.

An experimental test of the analogy between muon and radiative pion capture

Abstract Rate-measurements are reported on muon capture and radiative pion capture reactions in 6 Li yielding the ground state of 6 He.

Hyperfine effect in the MU - mesonic 11B atom and information on 11Be from muon capture measurements

Abstract The partial rates in the capture of muons by 11B were measured for the ground state and first excited level of 11Be. The transition between the hyperfine states of the μ-+11B mesonic atom was observed indirectly. The 320 keV γ-ray in 11Be, which follws the capture of the muon in 11B, was found to be broadened. Nuclear structure informations were obtained on the ground state and first excited state of 11Be.

A method to measure neutrino-gamma angular correlation in muon-capture

Abstract We consider the Doppler-broadening of the gamma-ray emitted by a bound-state excited in muon-capture in complex nuclei. This Doppler-broadened gamma spectrum is illustrated for special cases assuming realistic neutrino-gamma directional correlations and taking into account the finite energy-resolution of the Ge(Li) detector. It appears that the observation of the Doppler-broadened deexcitation gamma-ray spectrum offers a practical method to measure the neutrino-gamma directional correlation in muon-capture reactions.

Measurement of the induced pseudoscalar form factor in the capture of polarized muons by Si nuclei

Abstract The observation with high-resolution Ge detectors of the 1229 and 2171 keV gamma-rays emitted after the 28 Si(μ, ν) 28 Al(1 + , 2202 keV) reaction allowed us to determine the nuclear-amplitude ratio x ≡ M(2) M(−1) characteristic of this muon-capture reaction. Using the nuclear-structure dependent evaluation of various correction terms (model of Ciechanowicz), our result x = +0.254±0.034 provides for the induced pseudoscalar coupling g p the ratio g p g a (0.848m μ 2 ) = 3.4 ± 1.0 , to be compared to the PCAC prediction of g p g a = 7 . The model dependence of this apparent quenching remains to be assessed.

Investigation of the 64Zn states fed in the beta decay of 64Ga

Abstract A high-resolution Ge(Li) study of the 64 Ga decay supplemented by coincidence measurements has led to a new level scheme for 64 Zn. Five new 1 + levels above 4 MeV are found to be fed in the beta decay by allowed transitions. The reported level at 3.32 MeV is shown to be a complex of levels. The relevance of this work for the interpretation of betta-gamma circular polarization correlation experiments is briefly discussed.

Beta-neutrino correlation experiments on laser trapped K-38m, K-37

Laser trapping and cooling techniques are now being applied to the study of nuclear β-decay at several labs. A magneto-optical trap (MOT) provides a localized source of atoms suspended in space, so the low-energy recoiling nuclei can freely escape and be detected in coincidence with the β. This allows reconstruction of the neutrino momentum, and the deduction of the β-v correlation in a more direct fashion than previously possible. In addition, the nuclei can be polarized by atomic techniques, opening a new class of spin correlation measurements to test the degree to which parity is maximally violated in the weak interaction. Our present experiment has detected several hundred thousand recoil-β+ coincidences from the 0+ → 0+ pure Fermi decay of 38mK, produced at the on-line isotope separators TISOL and ISAC at TRIUMF. Our goal is to set constraints on non-Standard Model scalar bosons competitive with high-energy colliders and more conventional β-v correlation experiments.

Is there an indication for the existence of right-handed weak currents in nuclear beta decay?

The authors examine recent claims that experiments on neutron-decay are at variance with the standard V-A helicity structure of the standard model. The analysis presented here combines the neutron data with other recent experimental results and theoretical elaborations in the field of nuclear beta decay. If interpreted in the framework of left-right symmetric models, the data favour the existence of a right-handed weak gauge boson with mass between 207 and 369 GeV c2 at 95% CL. The fit using the standard V-A helicity structure has a chi 2 of 8.52 for four degrees of freedom and excludes the V-A solution at 2.53 standard deviations. This exclusion is due mainly to the new neutron asymmetry data and is in disagreement with the conclusions drawn from muon decay and from the KL-KS mass difference in the framework of manifest left-right symmetric models.

Positron polarization in the decay of polarized N-12: a precision test of the Standard Model

The longitudinal polarization of positrons emitted along and opposite to the nuclear spin direction has been measured in the decay of polarized N-12. The results are consistent with the Standard Model prediction. In manifest left-right symmetric models this measurement provides a lower bound of 310 GeV/c(2) at 90% CL on the mass of a possible right-handed gauge boson contributing to the electroweak interaction. In generalized versions of this model our measurement provides constraints complementary to those set by high-energy experiments