V. Kekelidze

Performance of an electromagnetic liquid krypton calorimeter based on a ribbon electrode tower structure

The NA48 collaboration is preparing a new experiment at CERN aiming to study CP violation in the K0-K0 system with an accuracy of 2 × 10−4 in the parameter Re(ϵ′/ϵ). Decays in two π0s will be recorded by a quasi-homogeneous liquid krypton calorimeter. A liquid krypton calorimeter has been chosen to combine good energy, position and time resolution with precise charge calibration and long-term stability. The prototype calorimeter incorporating the final design of the electrode read-out structure is presented in this paper. An energy resolution of ≃3.5%√E with a constant term smaller than 0.5% has been obtained. The time resolution was found to be better than 300 ps above 15 GeV.

NICA PROJECT AT JINR

The project of Nuclotron-based Ion Collider fAcility NICA/MPD (MultiPurpose Detector) under development at JINR (Dubna) is presented. The general goals of the project are providing of colliding beams for experimental studies of both hot and dense strongly interacting baryonic matter and spin physics (in collisions of polarized protons and deuterons). The first program requires providing of heavy ion collisions in the energy range of \( \sqrt {S_{NN} } \) = 4−11 GeV1 at average luminosity of L = 1 × 1027 cm−2 s−1 for 197Au79+ nuclei. The polarized beams mode is proposed to be used in energy sNN = 12−27 GeV (protons at luminosity of L ≥ 1 × 1030 cm−2 s−1. The key issue of the Project is application of cooling methods—stochastic and electron ones. The report contains description of the facility scheme and characteristics in heavy ion operation mode, status and plans of the project development.

Observation of the rare decay K-S ->pi(0)mu(+)mu(-)

A search for the decay KS→π0μ+μ−KS→π0μ+μ− has been made by the NA48/1 Collaboration at the CERN SPS accelerator. The data were collected during 2002 with a high-intensity KSKS beam. Six events were found with a background expectation of 0.22−0.11+0.18 events. Using a vector matrix element and unit form factor, the measured branching ratio is B(KS→π0μ+μ−)=[2.9−1.2+1.5(stat)±0.2(syst)]×10−9.A search for the decay K_S -> pi^0mu^+mu^- has been made by the NA48/1 Collaboration at the CERN SPS accelerator. The data were collected during 2002 with a high-intensity K_S beam. Six events were found with a background expectation of 0.22^+0.18_-0.11 event. Using a vector matrix element and unit form factor, the measured branching ratio is B(K_S -> pi^0mu^+mu^-)=[2.9^+1.5_-1.2(stat)+/-0.2(syst)]x10^{-9}.

Multilayer Scintillator Responses for Mo Observatory of Neutrino Experiment Studied Using a Prototype Detector MOON-1

An ensemble of multilayer scintillators is discussed as an option of the high-sensitivity detector MOON (Mo Observatory of Neutrinos) for spectroscopic measurements of neutrinoless double beta decays. A prototype detector MOON-1, which consists of 6-layer plastic scintillator plates, was built to study the photon responses of the MOON-type detector. The photon responses, i.e., the number of scintillation photons collected and the energy resolution, which are key elements for high-sensitivity experiments, are found to be 1835 � 30 photoelectrons for 976 keV electrons and � ¼ 2:9 � 0:1% (� E=E ¼ 6:8 � 0:3% in FWHM) at the Q�� � 3 MeV region, respectively. The multilayer plastic scintillator structure with high energy resolution as well as a good signal for the background suppression of � –� rays is crucial for the MOON-type detector to achieve inverted-hierarchy neutrino-mass sensitivity. It will also be useful for medical and other rare-decay experiments as well.

Neutrino studies in 100Mo and MOON - Mo Observatory of neutrinos

Abstract The MOON (Molybdenum Observatory Of Neutrinos) project is a hybrid ββ and solar ν experiment with 100 Mo. It aims at high sensitive studies of ββ decays with a sensitivity of m ν > ∼ 0.03 eV and real-time studies of pp and 7 Be solar νs. The double β rays from 100 Mo are measured in prompt coincidence for the 0νββ studies, and the inverse β rays from solar-ν captures of 100 Mo are measured in delayed coincidence with the subsequent β decay of 100 Tc. Measurements with good position resolution enable one to select true signals by spatial and time correlations.

A study of the semileptonic decays of neutral kaons

Dalitz plots of 74 000 Ke30 and 150 000 Kμ30 decays have been investigated to measure the t-dependence of the form factors ƒ+(t) and ƒ(t) describing the vector contribution to the decay matrix element. The decays were registered by a wire spark chamber spectrometer in the neutral beam of the Serpukhov accelerator. An analysis using a linear expansion of the form factors gives the slopes: λe+=0.0306±0.0034 for the Ke30 decays and λμ+ = 0.0427±0.0044, λ0 = 0.0341± 0.0067 for the Kμ30 decays. The ratio of the form factors ƒ− to ƒ+ has been found to be ξ(0)=ƒ−(0)/ƒ+(0)=−0.10±0.09. These results are compared with the relevant theoretical models. Together with the data of other experiments in which the parameters of muon and electron interactions are measured, the observed difference between λ+μ and λ+e gives some indication of the violation of μ-e universality.

KL0-KS0 transmission regeneration on hydrogen

The energy dependence of the modulus and phase of the KL0-KS0 regeneration amplitude on hydrogen in the range of 14–50 GeV has been investigated at the Serpukhov 70 GeV accelerator. It has been established that the modulus of the modified regeneration amplitude decreases with increasing momentum as 2|ƒ210(p)|/k = (0.84 ± 0.42) · p−0.50±0.15 mb. The amplitude phase is energy-independent and its mean value is ϕ210 = −132° ± 5°. The results obtained are compared with other experiments and with predictions of different theoretical models.

Heavy ion collider facility NICA at JINR (Dubna): status and development

The project of Nuclotron-based Ion Collider fAcility NICA/MPD (MultiPurpose Detector) under development at JINR (Dubna) is presented. The general goals of the project are providing of colliding beams for experimental studies of both hot and dense strongly interacting baryonic matter and spin physics (in collisions of polarized protons and deuterons). The first program requires providing of heavy ion collisions in the energy range of sNN = 411 GeV at average luminosity of L  110 27 cm 2 s 1 for 197 Au 79 nuclei. The polarized beams mode is proposed to be used in energy range of sNN = 1227 GeV (protons) at luminosity of L  110 cms. The report contains description of the facility scheme and characteristics in heavy ion operation mode, status and plans of the project development.

Neutral kaon regeneration on carbon in a momentum region of 16–40 GeV/c

Abstract The modulus and the phase of the K L o −K S o regeneration amplitude on carbon have been measured. In a momentum range of 16–40 GeV/ c the phase is constant within experimental error bars and coincides with the regeneration phase on hydrogen. Both the modulus and the phase of the regeneration amplitude on carbon are in agreement with optical model predictions.

MOON for a next-generation neutrino-less double-beta decay experiment; present status and perspective

The performance of the MOON detector for a next-generation neutrino-less double-beta decay experiment was evaluated by means of the Monte Carlo method. The MOON detector was found to be a feasible solution for the future experiment to search for the Majorana neutrino mass in the range of 100-30 meV.