Nucl.Instrum.Meth.A

The response of a sampling tile electromagnetic calorimeter was simulated for incident electrons in the 10–500 GeV energy range. The influence of tile to tile nonuniformity on the a and b coefficients of the calorimeter energy resolution parametrisation formula was investigated in detail. An energy resolution deterioration due to nonuniformity was observed, but it was shown that by calibrating the towers individually one can reduce this undesirable effect to reasonable limits. An explicit a and b coefficients dependence on σ non , the tile response nonuniformity standard deviation, was found. Our previous results on this dependence obtained by analytical methods using the electromagnetic shower mean profile universal parametrisation and the present results obtained by Monte Carlo simulation are compared and found to be in good agreement.

Phys. Lett. B

Based on observation [L.G. Afanasyev et al., Phys. Lett. B 308 (1993) 200] of 272±49 atoms formed by π + and π − an estimation of the atom lifetime in the ground (1S) state is obtained: τ 1 = (2.9 +∞ −2.1 ) · 10 −15 s or τ 1 > 0.6·10 −15 s at 90% confidence level. Atoms were produced in inclusive p Ta interactions at 70 GeV.

Phys.Rev.A

The method of hyperspherical "surface" functions has been applied to the calculation of eigenvalues and eigenfunctions of muonic molecular ions $~{3,4}\! H\! ed\mu $. Binding energies and nonradiative decay rates for the states of the total angular momentum $L=0,1,2$ have been obtained.

Phys. Rev. Lett.

The tensor analyzing power T20 for the reaction d↑+12C→p(0°)+X has been measured in the region of proton internal momenta k in light-cone dynamics up to 1 GeV/ c. Measurements have been carried out at Dubna Synchrophasotron with polarized deuteron beam at deuteron momenta up to 9 GeV/ c. When k increases the experimental values of T20 have a tendency to approach the value ( −0.3) obtained by the calculation based on the reduced nuclear amplitude method in which the quark degrees of freedom are taken into account.

Phys. Rev. D

From data accumulated over 6140 h with 172 g of enriched molybdenum (1.18 mol yr of Mo100) with the NEMO 2 detector in the Fréjus Underground Laboratory, a clear ββ2ν signal (1433 events) is observed, leading to a half-life T1/2=0.95±0.04(stat)±0.09(syst) 1019 yr. The experimental two-electron energy spectrum and the two-electron angular distribution are in agreement with the expected ones. Limits for ββ0ν decays to the ground state, excited states (21+ and 01+), and also with Majoron emission are given.

Nucl.Phys.B Proc.Suppl.

Nucl. Phys. A

This paper presents the results of an experiment in which the spin rotation parameters R and Ain π − p elastic scattering have been measured at energies 450, 530, 560 and 600 MeV. The experiment was performed on a pion channel of the PNPI synchrocyclotron. The main parts of the setup were a polarized proton target with horizontal spin orientation and a carbon-plate polarimeter consisting of multigap optical spark chambers with television read-out. A comparison of the obtained results with partial-wave analyses is given.

AIP Conf.Proc.

The short history of the development of frozen spin polarized targets at the Laboratory of Nuclear Problems JINR is given. The latest development is the target with a frozen spin polarization of protons in 1,2‐ propanediol with a paramagnetic CrVimpurity, intended for polarization parameter studies in np‐scattering at approximately 15 MeV neutron energy. The target of cylindrical shape of 2 cm diameter and 6 cm long with an initial polarization of 95±3% obtainable by the dynamic polarization technique is placed at a temperature about 20 mK in a magnetic field of 0.37 T generated by a magnetic system, which provides a large aperture for scattered particles. The relaxation time for the spin polarization is about 1000 hours.

AIP Conf.Proc.

A description of the recently installed mouable Polarized Proton Targe (MPT) at the JINR in Dubna is described. This target was acquired from Fermilab. The physics program based on the MPT at Dbna is outlined. (AIP)

Phys.Lett.B

Inclusive differential cross sections of 4,6,8 He, 6,7,8 Li formation in p 9 Be interactions at T p = 1 GeV have been measured. Enhancement of the 8 He yield is observed in the spectator momentum range ( P <300 MeV/ c ), which is evidence for the process of virtual Δ ++ -isobar knock-out from 9 Be. The ratio of the spectroscopic factors of (Δ ++ 8 He) and (p 8 Li) configurations in 9 Be is estimated to be (6±3) × 10 −4 .

Nucl.Instrum.Meth.A

The characteristics of narrow gap proportional chambers are presented. These chambers are applied in a beam part of the ISTRA-M apparatus in which very rare K − decays are studied.

Phys.Lett.B

The angular dependece of the pp elastic scattering spin correlation parameter was measured in the angular range from 60° to 97° CM at 14 energies between 1.96 and 2.23 GeV. A rapid decrease of the energy dependence of this observable at 90° CM is observed around 2.11 GeV kinetic energy. This agrees with the behavior of A oonn predicted on the basis of an exotic six-quark structure. The A oonn (90° CM ), together with the known differential cross section, allows the determination of the absolute value of the pure spin-singlet amplitude. The energy dependence of this amplitude shows a shoulder centered at 2.11 GeV, corresponding to a total mass of 2.735 GeV and an estimated width of 17 MeV.

Nucl. Instrum. Meth. A

A method for measuring the photomultiplier gain using a realistic photomultiplier response function is described. A precision of about 1% for the deconvoluted gain parameter can be achieved.

Phys.Rev.C

The results of a search for the 2β+ and Kβ+ decay modes of Kr78, in a coincidence experiment using a high pressure ionization chamber of enriched Kr78 inside an array of sodium iodine scintillators, are presented. After 4434 h of counting time, the half-life lower limits obtained are T1/2(Kβ+)0ν≥5.1×1021 yr and T1/2(2β+)0ν+2ν≥2.0×1021 yr at 68% C.L.

Nucl. Phys. B Proc. Suppl.

A Monte Carlo code has been developed to accurately simulate double-beta decay measurements. Coincident gamma rays, beta spectra, and angular correlations have been added to adequately simulate a complete $^{100}$Mo nuclear decay and provide corrections to experimentally determined detector efficiencies. This code has been used to strip certain low-background spectra obtained in the Homestake gold mine in Lead, SD, for the purpose of extremely sensitive materials assay for the construction of new, large, enriched germanium detectors. Assays as low as 9 μBq/g of $^{210}$Pb in lead shielding were obtained.

Nucl. Phys. B Proc. Suppl.

The data collected from the first set of three IGEX enriched germanium detectors have been analyzed. The best background obtained was less than 0.3 counts/keV/kg/y near 2 MeV, obtained in the Homestake gold mine in Lead, SD, USA. Data combined from all the detectors yield $T_{1/2}^{0 \nu} \geq 1.0 \times 10^{24}y(90 \% CL)$. The first detector produced in the second phase of the experiment is a 2.15 kg germanium crystal of 2.16 keV FWHM at 1332 keV. Several experiences with the first group of detectors have led to improvements in the mechanical design of the copper cryostat. Also, low background materials research done in the last two years has lowered the specific activity of the electroformed copper. The new detector is currently operating in the Homestake gold mine.

Nucl.Instrum.Meth.A

A magnetic spectrometer intended for a wide range of investigations of rare particle and nuclear processes is described. The spectrometer consists of cylindrical proportional chambers (∼ 15000 signal wires) with gas supply and gas leakage systems, cylindrical scintillation hodoscopes, a magnet, electronics with power supplies, and a data acquisition system. Basic characteristics of the spectrometer are discussed and results of first physics experiments are presented.

Z.Phys.A

The production of antiprotons in proton-nucleus and deuteron-nucleus collisions is analyzed with respect to one-step nucleon-nucleon (NN → NNp¯ p) and secondary Δ-nucleon (ΔN → NNN¯ p) production channels within a phase-space model incorporating the selfenergies of the baryons. It is found that contrary to nucleus-nucleus collisions the Δ induced reaction channels are of minor importance except at very low bombarding energies. The data from KEK are approximately reproduced when accounting for the internal momentum distribution of the deuteron which provides a natural explanation for the large enhancement of the ¯p cross section ind+A as compared top+A.

AIP Conf.Proc.

A status report on the reconstruction of the movable Proton Target (MP at JINR in Dubna is given. The MPT was originally built in Saclay and Argonne and then mounted and tested at Fermilab in 1988−1989. (AIP)

Z. Phys. C

We present data of several rescattering observables measured inn p elastic scattering between 0.80 and 1.10 GeV. The SATURNE II polarized beam of free neutrons obtained from the break-up of polarized deuterons was scattered on the Saclay polarized frozen-spin proton target. Three different configurations of beam and target polarization directions were used: the observablesDonon andKonno were measured with the normal-normal spin configuration at eight energies;Nonkk,Dos″ok andKos″ko were determined with the longitudinal-longitudinal configuration at six energies;Nonsk,Dos″ok andKos″so with the sideway-longitudinal configuration at six energies. Part of the data was obtained with an unpolarized CH2 target where only the two spin-index polarization transfer parametersKos″ko andKos″so were determined. Data are compared with phase shift analyses predictions and with the LAMPF results at 0.788 GeV. Present results are the first measurements of rescattering observables above 0.80 GeV. They provide an important contribution to any future theoretical or phenomenological analysis.

AIP Conf.Proc.

Continuous improvements of SATURNE polarized target resulted in a flexible and reliable facility for spin physics. For polarized neutron target, two cartridges loaded with 6LiD and 6LiH are set in the refrigerator and can be quickly inserted in the beam. The polarized proton target is a 70 cm3 cartridge loaded with Pentanol‐2, a promising material according to the results obtained. Angular distribution as a function of a kinematically conjugate angle and coplanarity in nucleon‐nucleon scattering is shown for different targets.

10.2172/1156336