Multilayer aerogel for compact RICH detectors

This paper covers some of the latest achievements in the testing of multi–index silica aerogel. Optical bench measurements and preliminary results from a recently performed charged particle beam test are presented. This work is part of an effort aimed at assessing the potential of multilayer aerogel as a radiator for compact, proximity focused ring imaging Cherenkov detectors

Spin physics with antiprotons

New possibilities arising from the availability at GSI of antiproton beams, possibly polarised, are discussed. The investigation of the nucleon structure can be boosted by accessing in Drell-Yan processes experimental asymmetries related to cross-sections in which the parton distribution functions (PDF) only appear, without any contribution from fragmentation functions; such processes are not affected by the chiral suppression of the transversity function $h_1(x)$. Spin asymmetries in hyperon production and Single Spin Asymmetries are discussed as well, together with further items like electric and magnetic nucleonic form factors and open charm production. Counting rates estimations are provided for each physical case. The sketch of a possible experimental apparatus is proposed.Comment: Presented for the proceedings of ASI "Spin and Symmetry", Prague, July 5-10, 2004, to be published in Czech. J. Phys. 55 (2005

Fast Photon Detection for Particle Identification with COMPASS RICH-1

Particle identification at high rates is an important challenge for many current and future high-energy physics experiments. The upgrade of the COMPASS RICH-1 detector requires a new technique for Cherenkov photon detection at count rates of several $10^6$ per channel in the central detector region, and a read-out system allowing for trigger rates of up to 100 kHz. To cope with these requirements, the photon detectors in the central region have been replaced with the detection system described in this paper. In the peripheral regions, the existing multi-wire proportional chambers with CsI photocathode are now read out via a new system employing APV pre-amplifiers and flash ADC chips. The new detection system consists of multi-anode photomultiplier tubes (MAPMT) and fast read-out electronics based on the MAD4 discriminator and the F1-TDC chip. The RICH-1 is in operation in its upgraded version for the 2006 CERN SPS run. We present the photon detection design, constructive aspects and the first Cherenkov light in the detector.Comment: Proceedings of the Imaging 2006 conference, Stockholm, Sweden, 27-30 June 2006, 5 pages, 6 figures, to appear in NIM A; corrected typo in caption of Fig.

Fast photon detection for the COMPASS RICH detector

The COMPASS experiment at the SPS accelerator at CERN uses a large scale Ring Imaging CHerenkov detector (RICH) to identify pions, kaons and protons in a wide momentum range. For the data taking in 2006, the COMPASS RICH has been upgraded in the central photon detection area (25% of the surface) with a new technology to detect Cherenkov photons at very high count rates of several 10^6 per second and channel and a new dead-time free read-out system, which allows trigger rates up to 100 kHz. The Cherenkov photons are detected by an array of 576 visible and ultra-violet sensitive multi-anode photomultipliers with 16 channels each. The upgraded detector showed an excellent performance during the 2006 data taking.Comment: Proceeding of the IPRD06 conference (Siena, Okt. 06

Nucleon-nucleon elastic scattering analysis to 2.5 GeV

A partial-wave analysis of NN elastic scattering data has been completed. This analysis covers an expanded energy range, from threshold to a laboratory kinetic energy of 2.5 GeV, in order to include recent elastic pp scattering data from the EDDA collaboration. The results of both single-energy and energy-dependent analyses are described.Comment: 23 pages of text. Postscript files for the figures are available from ftp://clsaid.phys.vt.edu/pub/said/n

The Identification of rDNA-ITS and Localization of heterochronic gene In Meloidogyne javanica

根结线虫是重要的植物内寄生线虫。本论文以同安农田采集的番茄病根中爪哇根结线虫为实验材料，对病根进行解剖，收集成虫、二期幼虫和卵块。通过对根结线虫胚胎发育和生活史中各期虫体形态的观察，进一步定种为爪哇根结线虫。通过感染室内土培番茄，使得爪哇根结线虫在实验室得到进一步的扩大培养，为后续实验的进行提供了材料。利用rRNA基因间隔序列的保守性引物对来自不同宿主的爪哇根结线虫和南方根结线虫的rDNA-ITS1和rDNA-ITS2序列进行了扩增，与Genebank中根结线虫的ITS1序列在clustalX软件中进行了分析，构建系统发生树和遗传距离矩阵。分析可知，来源于番茄根内和蒲公英根内的爪哇根结线虫rD...Root-knot nematodes are important endo-parasites in economic plants. The roots of tomatoes infected with M. javanica were got from the field of Tong’an rural area and roots were dissected.The egg masses, pre-parasitic juveniles and female adults of M. javanica were collected in the lab.The embryo development and different stages of life cycle of root-knot nematode were observed. In order to obtain...学位：理学硕士院系专业：生命科学学院生物学系_动物学学号：20032601