A. Stevens

Evidence for the decay K+ ---> pi+ neutrino anti-neutrino

An event consistent with the signature expected for the rare kaon decay K+ --> pi+ nu anti-nu has been observed. In the pion momentum region examined, 211 pi+ nu anti-nu, the branching ratio is (4.2 +9.7/-3.5) x E-10.

The RHIC design overview

The salient performance objectives for the Relativistic Heavy Ion Collider (RHIC) are presented and the rationale for the design choices of the major collider systems is conveyed. RHIC provides collisions of heavy ions covering the entire mass range from protons to gold. For the prototypical case of Au-on-Au, one obtains energies up to 100 GeV/n per beam and luminosities of B2 � 10 26 cm � 2 s � 1 , averaged over a 10-h storage time. Operation with polarized protons is also possible. The overall accelerator complex used for gold ions consists of the Tandem Van de Graaff, the Booster, the AGS, and the Collider itself, and the scenario for the beam transfer between machines is described. The two separate collider rings cross at six interaction points, where the lattice design provides low-beta insertions for maximum luminosity. The interaction diamond length of o20 cm rms is achieved by bunched beam operation and holding the 56 bunches in a 197 MHz radio-frequency (RF) system after their acceleration in a 28 MHz RF system. The rings are constructed with superconducting magnets, which have a cold bore aperture of 6.9 cm in the arcs. The RHIC specific design challenges posed by intrabeam scattering of heavy ions, passage through transition energy with slow-ramping superconducting magnets, and control of magnetic errors in the low-beta triplet quadrupoles are addressed. r 2002 Elsevier Science B.V. All rights reserved.

OBSERVATION OF THE DECAY K+ PI + GAMMA GAMMA

The first observation of the decay K + ! � + is reported. A total of 31 events was observed with an estimated background of 5.1±3.3 events in the � + momentum range from 100 MeV/c to 180 MeV/c. The corresponding partial branching ratio, B(K + ! � + , 100 MeV/c < P�+ < 180 MeV/c), is (6.0±1.5{stat}±0.7{sys})×10 7 . No K + ! � + decay was observed in the � + momentum region greater than 215 MeV/c. The observed � + momentum spectrum is compared with the predictions of chiral perturbation theory.

Observation of the decay K+ ---> pi+ mu+ mu-

We have observed the rare decay K+ --> pi+ mu+ mu- and measured the branching ratio Gamma(K+ --> pi+ mu+ mu-)/Gamma(K+ --> all) = (5.0 +/- 0.4 (stat.) +/- 0.7 (sys.) +/- 0.6 (theor.)) x 10^{-8}. We compare this result with predictions from chiral perturbation theory and estimates based on the decay K+ --> pi+ e+ e-.

A detector to search for K+ → π+ νν

Abstract The detector built for experiment 787 to measure the decay K + → π + ν ν at Brookhaven National Laboratory is describe

Superconducting Magnets for the CBA Project

Abstract The superconducting magnets that were designed and tested for the BNL colliding beam accelerator are described, including dipoles, quadrupoles and trim coils. The dipoles had an effective length of 436 cm, a good field aperture of 8.8 cm diameter, and were designed for an operating field of 5.28 T in a temperature range between 2.6 K and 3.8 K (provided by supercritical helium). The quadrupoles had the same aperture, an effective length of 138.5 cm, and were designed to operate in series with the dipoles, with a gradient of 70.8 T/m. The dipoles incorporated internal sextupole, octupole, and decapole trim coil windings; the quadrupole trim coils consisted of dipole, quadrupole, and dodecapole windings. The design, construction, and performance (training, field quality, quench protection characteristics) of prototype magnets are discussed in considerable detail.

Search for the decay K+--> pi + nu nu -bar.

An upper limit on the branching ratio for the decay

Search for a light Higgs boson in the decay K+--> pi +H, H--> micro+ micro-

K^+ \! \rightarrow \! \pi^+ \nu \overline{\nu}

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

is set at

Search for the decay [ital K][sup +][r arrow][pi][sup +][nu][bar [nu]]

2.4 \times 10^{-9}