Scanning a Silicon Photomultiplier with a Laser Beam

Physics of Particles and Nuclei Letters - The Silicon Photomultiplier (SiPM) is a novel semiconducting photodetector which can detect single photons. It consists of many microcells (pixels)...     

Forced vibrations of a boxed shell of square cross-section

We construct the solution of the problem on the steady-state vibrations of a finite boxed shell of square cross-section with symmetry conditions at the shell ends. We present the dispersion curves, find the natural frequencies, and study the stress distribution in the shell. We obtain a simple formula for the approximate analysis of the shell in the case of low-frequency vibrations on the basis of the expansion of the solution in two small parameters and on the Lagrange interpolation formula.     

Design and preliminary test results of Daya Bay RPC modules

Resistive Plate Chamber (RPC) modules will be used as one part of the cosmic muon veto system in the Daya Bay reactor neutrino experiment. A total of 189 RPC modules will cover the three water pools in the experiment. To achieve track reconstruction and high efficiency, each module consists of 4 layers, each of which contains two sizes of bare chambers. The placement of bare chambers is reversed in different layers to reduce the overlapping dead areas. The module efficiency and patch efficiency were studied both in simulation and test of the data analysis. 143 modules have been constructed and tested. The preliminary study shows that the module and patch 3 out of 4 layers efficiency reaches about 98%.     

Investigation of β–ν Angular Correlation in the β+ Decay of 18Ne and 14O

The – angular correlation in the ⁺ decay of ¹⁸Ne and ¹⁴O has been investigated using a new experimental technique. The technique is based on the precise measurement of the energy Doppler shift of a -quantum following the ^± decay. The measurement with the ¹⁸Ne isotope gives the – angular correlation coefficient = +1.06 ±0.19 which corresponds to a constraint on the scalar interaction of {|C_S|²+|C'_S|²} 0.29|C _V|. An inter-atomic interaction between the ¹⁴O daughter atom (¹⁴N) and a CO complex has been studied in a measurement with the ¹⁴O isotope.     

Study of 2β-decay of 100Mo and 82Se using the NEMO3 detector

After analysis of 5797 h of data from the detector NEMO3, new limits on neutrinoless double beta decay of ¹⁰⁰Mo (T _1/2>3.1×10²³y, 90% CL) and ⁸²Se (_{T 1/2}>1.4×10²³y, 90% CL) have been obtained. The corresponding limits on the effective majorana neutrino mass are: 〈m _v〉<(0.8–1.2) eV and 〈m _v〉<(1.5–3.1) eV, respectively. Also the limits on double-beta decay with Majoron emission are: T _1/2>1.4×10²²y (90% CL) for ¹⁰⁰Mo and T _1/2>1.2×10²²y (90% CL) for ⁸²Se. Corresponding bounds on the Majoron-neutrino coupling constant are 〈 g _ee〉<(0.5–0.9)×10^?4 and <(0.7?1.6)×10^?4. Two-neutrino 2β-decay half-lives have been measured with a high accuracy, $T_{1/2}^{100_{Mo} } = [7.68 \pm 0.02(stat) \pm 0.54(syst)] \times 10^{18} y$ and $T_{1/2}^{82_{Se} } = [10.3 \pm 0.3(stat) \pm 0.7(syst)] \times 10^{19} y$ .     

First results of the search for neutrinoless double-beta decay with the NEMO 3 detector

The NEMO 3 detector, which has been operating in the Fréjus underground laboratory since February 2003, is devoted to the search for neutrinoless double-beta decay (beta beta 0v). The half-lives of the two neutrino double-beta decay (beta beta 2v) have been measured for 100Mo and 82Se. After 389 effective days of data collection from February 2003 until September 2004 (phase I), no evidence for neutrinoless double-beta decay was found from approximately 7 kg of 100Mo and approximately 1 kg of 82Se. The corresponding limits are T1/2(beta beta0v) > 4.6 x 10(23) yr for 100Mo and T1/2(beta beta 0v) > 1.0 x 10(23) yr for 82Se (90% C.L.). Depending on the nuclear matrix element calculation, the limits for the effective Majorana neutrino mass are < 0.7-2.8 e/v for 100Mo and < 1.7-4.9 eV for 82Se.