Performance of a CsI(Tl) calorimeter in an experiment with stopped K+'s

The performance of the photon detector constructed for the search of T-violation in the decay K^+ -> pi^0 mu^+ nu is presented. The specific features of this detector consisting of 768 CsI(Tl) crystals with PIN photodiode readout for high precision measurement of T-odd correlations in the decays of positive kaons are considered.Comment: 11 pages, 10 figures, talk at the INSTR02 Conference, Novosibirsk, Russia, February 28 - March 6, 200

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