21 research outputs found
Search for the decay in the momentum region
We have searched for the decay in the kinematic
region with pion momentum below the peak. One event was
observed, consistent with the background estimate of . This
implies an upper limit on
(90% C.L.), consistent with the recently measured branching ratio of
, obtained using the standard model
spectrum and the kinematic region above the peak. The
same data were used to search for , where is a weakly
interacting neutral particle or system of particles with .Comment: 4 pages, 2 figure
Search for the decay K+ to pi+ gamma gamma in the pi+ momentum region P>213 MeV/c
We have searched for the K+ to pi+ gamma gamma decay in the kinematic region
with pi+ momentum close to the end point. No events were observed, and the 90%
confidence-level upper limit on the partial branching ratio was obtained, B(K+
to pi+ gamma gamma, P>213 MeV/c) < 8.3 x 10-9 under the assumption of chiral
perturbation theory including next-to-leading order ``unitarity'' corrections.
The same data were used to determine an upper limit on the K+ to pi+ gamma
branching ratio of 2.3 x 10-9 at the 90% confidence level.Comment: 15 pages, 3 figures; no change in the results, accepted for
publication in Physics Letters
Further search for the decay in the momentum region P < 195 MeV/c
We report the results of a search for the decay
in the kinematic region with momentum MeV/c using the
data collected by the E787 experiment at BNL. No events were observed. When
combined with our previous search in this region, one candidate event with an
expected background of events results in a 90% C.L. upper limit
of on the branching ratio of .
We also report improved limits on the rates of and where are hypothetical, massless, long-lived
neutral particles.Comment: 5 pages, 3 figures, Accepted for publication in Phys. Rev.
Recommended from our members
Recent performance of the TRIUMF cyclotron and status of the facility
In December 1994, TRIUMF celebrated 20 years of operation. The peak intensity has been increased over the years to the present level of approximately 200 {micro}A on beam line 1A. Polarized beam currents in excess of 20 {micro}A are available although most users prefer lower intensity, higher quality slit-tailored polarized beams. The cyclotron simultaneously extracts three beams: one at 500 MeV for meson production, a lower intensity beam on beam line 4 for nuclear physics, nuclear chemistry, or astrophysics experiments, and a low energy beam (65--120 MeV, from a few nA up to 100 {micro}A) on beam line 2C for isotope production or proton therapy. The yearly total integrated extracted beam current is now in the order of 600 mAh per year. Beam delivery is in excess of 5,000 hours per year with beam availability consistently around 90%, serving as many as 8 experimental stations simultaneously. An additional simultaneous extraction line is planned for the new ISAC facility. With the present polarized beam current capability, the operation of polarized beams for the beam line 4 experiments will be possible simultaneously with the operation of the ISAC facility up to levels of 20 {micro}A, 500 MeV, on target. Recent facility developments will also be reported