Search

K± → e±νπ0 decays have been studied using the KMN setup at the Institute for High Energy Physics (Protvino). The experiment has been performed in the 36-GeV/c hadron beams of the IHEP accelerator. The accumulated data allow us to select ∼1.08M candidates for Ke3 decays. Analyzing the Dalitz plot of these events, we estimate the linear slope of the charge form factor to be λ+ = [30.44 ± 0.83(stat.) ± 0.74(syst.)] × 10−3.

A structure of the multicomputer data acquisition complex for the Hyperon-M experiment at the U-70 accelerator (Protvino, Russia) is described. This complex has been designed to collect and merge data from several particle detectors, the electronic systems of which are made either to the MISS or SUMMA standard. The MISS system is autonomously operated under control of a special ЛЭ-74 controller that collects information in its internal buffer storage during a beam spill. The data acquired are combined with the information from the SUMMA electronics and are copied to an external storage device (a hard disk of a computer) in intervals between spills. On the contrary, software control is needed for the SUMMA electronics to read data on each event. Software-and hardware-based methods are used to provide joint operation of the electronic systems made to diverse standards and guarantee that the streams of incoming data are correctly merged. The problems of net interactions between different parts of the multicomputer system and monitoring of this system are analyzed.

The results are presented for the charge asymmetry of the Dalitz plot parameters g, h, and k measured for K± → π±π0π0 decays. The experiment has been carried out in the 35-GeV/c kaon beams at the IHEP accelerator. The g, h, and k parameters appear to be identical for K+ and K− decays within the experimental uncertainty. In particular, a value of (0.2 ± 1.9) × 10−3 is obtained for the charge asymmetry Ag = (g+ − g−)/(g+ + g−) of the Dalitz plot slope.

The characteristics of a gas ionization calorimeter with planar electrode geometry have been studied in hadron and electron beams with momenta from 19 to 50 GeV/ c . The calorimeter was filled with a 95% Ar + 5% CF 4 gas mixture. Absorbers were made of uranium and steel. The dependencies of energy resolution on gas pressure and absorber thickness are presented. The signal-to-noise and electron-to-hadron ratios are discussed.

The charge asymmetry of the g, h, and k Dalitz plot parameters for $K^{\pm}\to\pi^{\pm}\pi^0\pi^0$ decays has been measured with 35 GeV/c hadron beams at the 70 GeV IHEP accelerator. The g, h and k values obtained appear to be identical for $K^{\pm}\to\pi^{\pm}\pi^0\pi^0$ decays within the errors quoted. In particular, the charge asymmetry $A_g = (g^+ - g^-)/(g^+ + g^-)$ of the slope g is equal to $(0.2 \pm 1.9)\cdot 10^{-3}$., Comment: 18 pages, 15 figures

The calibration and monitoring system for the PHENIX lead-scintillator electromagnetic calorimeter is described along with the experience obtained in using this system to calibrate calorimeter modules with cosmic rays. The system is based on a UV laser which delivers light to each module through a series of optical fibers and splitters that is monitored at various points using silicon and vacuum photodiodes. Results are given from a prototype system based on a nitrogen laser which was used to monitor the stability of several modules, as well as to set the gains of the phototubes and establish the energy calibration of all calorimeter modules before installation into the final detector. A description of the final system to be used in PHENIX, based on a high power YAG laser, is also given.