A time projection chamber (TPC) is a strong candidate for the central tracker of the international linear collider (ILC) experiment and we have been conducting a series of cosmic ray experiments ...under a magnetic field up to 4T, using a small prototype TPC with a replaceable readout device: multi-wire proportional chamber (MWPC) or gas electron multiplier (GEM). We first confirmed that the MWPC readout could not be a fall-back option of the ILC-TPC under a strong axial magnetic field of 4T since its spatial resolution suffered severely from the so called E×B effect in the vicinity of the wire planes. The GEM readout, on the other hand, was found to be virtually free from the E×B effect and gave the resolution determined by the transverse diffusion of the drift electrons (diffusion limited). Furthermore, GEMs allow a wider choice of gas mixtures than MWPCs. Among the gases we tried so far a mixture of Ar–CF4-isobutane seems promising as the operating gas of the ILC-TPC because of its small diffusion constant especially under a strong magnetic field. We report the spatial resolution obtained with the GEM readout in this gas mixture. Also presented is the spatial resolution of a GEM-based ILC-TPC estimated from the measurement with the prototype.
Measuring liquid level and solution concentration play an important role in commercial and technological applications. For years, polymer optical fibers (POFs) have been very attractive for ...industrial applications because of their unique characteristics. In this work, we created simple, low cost and efficient set-up for sensing liquid level and solution concentration using POFs. We have calculated the acceptance angle of the POF to be 30°from numerical aperture (NA) measurements (NA 0.500).Images of a single POF showed the presence of impurities within the fiber which can contribute to power loss of the transmitted light. Light leakage was also observed when the fiber was bent to a tight radius, i.e. beyond its minimum bend radius of 15 mm. The experimental results show that as liquid level increases, the output power decreases. Furthermore, when the liquid concentration was increased, its response showed a greater loss of optical power due to the light rays in the submerged region of the POF tend to be refracted out of the fiber instead of being totally internally reflected and transmitted when index of refraction of the surrounding liquid medium is increased.
The results of a beam test performed at the KEK PS in June 2005 are presented. Drift properties of an argon–isobutane mixture have been accurately measured and compared with predictions at magnetic ...fields between 0 and 1
T. The r.m.s. point resolution of a padrow is compared with simulation and with an analytical calculation. The fundamental limitations due to detector geometry and gas properties are reviewed and the measured performances of the detector are found to be close to this limit. A numerical application to the case of a linear collider Time Projection Chamber (TPC) is presented.
We conducted a series of beam tests of prototype TPCs for the International Linear Collider (ILC) experiment, equipped with an MWPC, a MicroMEGAS, or GEMs as a readout device. The prototype operated ...successfully in a test beam at KEK under an axial magnetic field of up to 1
T. The analysis of data is now in progress and some of the preliminary results obtained with GEMs and MicroMEGAS are presented along with our interpretation. Also given is the extrapolation of the obtained spatial resolution to that of a large TPC expected as the central tracker of the ILC experiment.
A time projection chamber (TPC) is a strong candidate for the central tracker of the international linear collider (ILC) experiment and we have been conducting a series of cosmic ray experiments ...under a magnetic field up to 4 T, using a small prototype TPC with a replaceable readout device: multi-wire proportional chamber (MWPC) or gas electron multiplier (GEM). We first confirmed that the MWPC readout could not be a fall-back option of the ILC-TPC under a strong axial magnetic field of 4 T since its spatial resolution suffered severely from the so called E x B effect in the vicinity of the wire planes. The GEM readout, on the other hand, was found to be virtually free from the E x B effect as had been expected and gave the resolution determined by the transverse diffusion of the drift electrons (diffusion limited). Furthermore, GEMs allow a wider choice of gas mixtures than MWPCs. Among the gases we tried so far a mixture of Ar-CF4-isobutane, in which MWPCs could be prone to discharges, seems promising as the operating gas of the ILC-TPC because of its small diffusion constant especially under a strong magnetic field. We report the measured drift properties of this mixture including the diffusion constant as a function of the electric field and compare them with the predictions of Magboltz. Also presented is the spatial resolution of a GEM-based ILC-TPC estimated from the measurement with the prototype.
El estrés abiótico es una de las principales causas de las pérdidas de las producciones agrícolas a nivel mundial. Los reguladores del crecimiento vegetal tales como el ácido abscícico, el etileno, ...el ácido jasmónico y el ácido salicílico son esenciales en la respuesta de las plantas al estrés abiótico. Se describen las generalidades de estas moléculas así como su función en la respuesta de la planta frente al estrés abiótico.
The abiotic stress is one of the most significative cause of the agricultural economic losses around the world. Plant growth regulators as: abscisic acid , ethylene, jasmonic acid and salicylic acid are essentials in the abiotic stress plant response. The molecular and the other chemical properties ofthe main plant growth regulators as well as their influence on plant response against the abiotic stress are described in this paper.
A GEM TPC end panel pre-prototype was constructed for a large LC-TPC prototype to test its basic design philosophy and some of its engineering details. Its interim test results are presented.
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