S. Kabe

Further evidence for the decay K+ ---> pi+ neutrino anti-neutrino

Additional evidence for the rare kaon decay K+ to pi+ neutrino-antineutrino has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion momentum region examined, 211<P<229 MeV/c, bringing the total for the combined data set to two. Including all data taken, the backgrounds were estimated to contribute 0.15 pm 0.05 events. The branching ratio is B=1.57^{+1.75}_{-0.82} 10^{-10}.

Further Evidence for the DecayK+→π+νν¯

Additional evidence for the rare kaon decay K+ to pi+ neutrino-antineutrino has been found in a new data set with comparable sensitivity to the previously reported result. One new event was observed in the pion momentum region examined, 211<P<229 MeV/c, bringing the total for the combined data set to two. Including all data taken, the backgrounds were estimated to contribute 0.15 pm 0.05 events. The branching ratio is B=1.57^{+1.75}_{-0.82} 10^{-10}.

Further search for the decay K+-->pi(+)nunu;

A search for additional evidence for the rare kaon decay K^+ -->pi^+ nu nubar has been made with a new data set comparable in sensitivity to the previous exposure that produced a single event.A search for additional evidence for the rare kaon decay K{sup +}{yields}{pi}{sup +}{nu}{nu} (bar sign) has been made with a new data set comparable in sensitivity to the previous exposure that produced a single event. No new events were found in the pion momentum region examined, 211<P<229 MeV/c . Including a reanalysis of the original data set, the backgrounds were estimated to contribute 0.08{+-}0.02 events. Based on one observed event, the new branching ratio is B(K{sup +}{yields}{pi}{sup +}{nu} {nu}(bar sign))=1.5{sup +3.4}{sub -1.2}x10{sup -10} . (c) 2000 The American Physical Society.

Measurement of structure-dependent K+ --> m(+)nu(m)gamma decay

We report the first measurement of a structure dependent component in the decay K^+ ->mu^+ nu gamma. Using the kinematic region where the muon kinetic energy is greater than 137 MeV and the photon energy is greater than 90 MeV, we find that the absolute value of the sum of the vector and axial-vector form factors is |F_V+F_A| =0.165 pm 0.007 pm 0.011. This corresponds to a branching ratio of BR(SD^+) = (1.33 pm 0.12 pm 0.18) times 10^{-5}. We also set the limit -0.04

Performance of fine mesh photomultiplier tubes designed for an undoped CsI endcap photon detector

Abstract We have developed two types of fine-mesh photomultiplier tubes for an undoped-CsI endcap photon detector installed in a strong axial magnetic field. These photomultiplier tubes have ultraviolet-transmitting glass windows, backed by large-area bialkali photocathodes, in order to efficiently detect scintillation light from undoped-CsI crystals. A gain of more than 2 × 10 5 , in a magnetic field of 1.0 T, was obtained from these tubes with 19-stage fine-mesh dynodes. Gain drops caused by the magnetic field and by high anode currents were investigated. Several performance criteria of the tubes were studied: gain, quantum efficiency, linearity, noise, and transit time spread.

A massive, fine-grained detector for the elastic reactions induced by neutrinos in the GeV energy region

Abstract This paper describes the design criteria, construction, and performance of a detector to study neutral and charged current elastic neutrino interactions induced by neutrinos of average energy approximately 1 GeV from the Brookhaven National Laboratory Alternating Gradient Synchrotron.

Beam tests of the prototype level-1 trigger system and drift tubes with field-shapers proposed for the SDC barrel muon system

Abstract Mini-tower beam tests were carried out at a test beam line of KEK-PS in order to study the performance of the prototype level-1 trigger system and drift tubes with field-shapers originally designed for the SDC barrel muon detector at the SSC. A mini-tower of 10 layers, 31 drift tubes in total, and a prototype level-1 trigger module were designed and fabricated for the tests. The spatial resolution of about 230 μm was obtained for the tubes. Relatively high rates of multi-pulse signals were observed for most of the tubes. The trigger module designed at KEK using a logic delta- T method was studied for various trigger logics and its performance was found to be very satisfactory.

Measurement of Structure-Dependent K+→μ+νμγ Decay

We report the first measurement of a structure dependent component in the decay K^+ ->mu^+ nu gamma. Using the kinematic region where the muon kinetic energy is greater than 137 MeV and the photon energy is greater than 90 MeV, we find that the absolute value of the sum of the vector and axial-vector form factors is |F_V+F_A| =0.165 pm 0.007 pm 0.011. This corresponds to a branching ratio of BR(SD^+) = (1.33 pm 0.12 pm 0.18) times 10^{-5}. We also set the limit -0.04

Search for the Decay K+ -> pi+ pi0 nu nubar

The first search for the decay K^+ -> pi^+ pi^0 nu nubar has been performed with the E787 detector at BNL. Based on zero events observed in the kinematical search region defined by 90 MeV/c pi^+ pi^0 nu nubar) < 4.3 x 10^{-5} at 90% confidence level is established.

Search for the decay K+ ---> pi+ pi0 neutrino anti-neutrino

The first search for the decay K^+ -> pi^+ pi^0 nu nubar has been performed with the E787 detector at BNL. Based on zero events observed in the kinematical search region defined by 90 MeV/c pi^+ pi^0 nu nubar) < 4.3 x 10^{-5} at 90% confidence level is established.