Recent results on the properties of two-phase argon avalanche detectors

The characteristic properties of two-phase Ar avalanche detectors, including those obtained with CsI photocathode, are further studied. Such detectors are relevant in the field of coherent neutrino-nucleus scattering and dark matter search experiments. The detectors investigated comprised a 1 cm thick liquid Ar layer followed by a triple-GEM multiplier. In these detectors, typical gains reaching 10000 were obtained with good reproducibility and a stable operation for at least one day was demonstrated. Amplitude and pulse-shape characteristics are presented under irradiation with X-rays, gamma-rays and neutrons from different radioactive sources. The detection of both primary scintillation and ionization signals at higher gains, at a deposited energy of 60 keV, has been demonstrated.Comment: 6 pages, 11 figures. Presented at Xth Int. Conf. for Collid. Beam Phys., Feb 28 - March 6, 2008, Novosibirsk, to be published in Nucl. Instr. Meth.

Dalitz Analysis of B->K+pi+pi- and B->K+K+pi-

We report results of the Dalitz analysis of the three-body charmless B->K+pi+pi- and B->K+K+K- decays based on a 140fb^{-1} data sample collected with the Belle detector. Measurements of branching fractions for quasi-two-body decays to scalar-pseudoscalar states: B-> f_0(980)K^+, B-> K^*_0(1430)^0 pi+, and to vector-pseudoscalar states: B-> K^*(892)^0 pi+, B-> rho^0 K+, B-> phi K+ are presented. Upper limits on decays to some pseudoscalar-tensor final states are reported. We also report the new measurement of the B-> chi_c K+ branching fraction in two chi_c decay channels: chi_c-> pi+ pi- and chi_c-> K+K-.Comment: ICHEP04 proceedings, 4 pages, 1 figur

Evaluation of the Systemic and Regional Antibiotic Therapy Effectiveness as Part of Complex Therapy in Patients with Locally Spread Breast Cancer

In recent years, breast cancer is the most common oncologic pathology and the most common cause of disability among women in developed countries.The aim of the study. To improve direct and long-term results of treatment in patients with locally spread forms of breast cancer (LSBC) by accelerated regression of perifocal inflammatory changes using selective intraarterial application of antibiotics; improving patients' quality of life.Materials and methods. The main sample consisted of 109 patients.The control group included 65 (61 %) clinical cases of LSBC who were performed series of courses of intravenous systemic polychemotherapy (SPHT) as neoadjuvant therapy accompanied by systemic intravenous antibiotic therapy. The study group consisted of 42 (39 %) patients who were performed selective intraarterial neoadjuvant polychemotherapy course with simultaneous regional use of antibiotic therapy in the intraarterial administration.Results. The regional administration of antibiotics as a part of the complex neoadjuvant therapy, along with the method of selective intraarterial polychemotherapy, has a positive effect on the linear and chronometric regression of perifocal inflammatory changes around the focus of the primary inoperable LSBC, which positively affects the somatic and psychological patient's state and increases the quality of his life.Conclusions. The complex regional impact on the affected organ has a statistically confirmed better effect with bright holistic features, demonstrating the additive synergism of selective techniques.The selective intraarterial antibiotic therapy does not require additional time and material costs while increasing the efficiency of the method. The versatile advanced approach positively affects the somatic and psychological state of the patient

Study of ion feedback in multi-GEM structures

We study the feedback of positive ions in triple and quadruple Gas Electron Multiplier (GEM) detectors. The effects of GEM hole diameter, detector gain, applied voltages, number of GEMs and other parameters on ion feedback are investigated in detail. In particular, it was found that the ion feedback is independent of the gas mixture and the pressure. In the optimized multi-GEM structure, the ion feedback current can be suppressed down to 0.5% of the anode current, at a drift field of 0.1 kV/cm and gain of 10^4. A simple model of ion feedback in multi-GEM structures is suggested. The results obtained are relevant to the performance of time projection chambers and gas photomultipliers.Comment: 9 pages, 11 figures. Submitted to Nucl. Instr. and Meth.

High pressure operation of the triple-GEM detector in pure Ne, Ar and Xe

We study the performance of the triple-GEM (Gas Electron Multiplier) detector in pure noble gases Ne, Ar and Xe, at different pressures varying from 1 to 10 atm. In Ar and Xe, the maximum attainable gain of the detector abruptly drops down for pressures exceeding 3 atm. In contrast, the maximum gain in Ne was found to increase with pressure, reaching a value of 100,000 at 7 atm. The results obtained are of particular interest for developing noble gas-based cryogenic particle detectors for solar neutrino and dark matter search.Comment: 7 pages, 4 figures. Submitted to Nucl. Instr. and Meth. A as a letter to the Edito