Spatial Resolution of a Micromegas-TPC Using the Charge Dispersion Signal

The Time Projection Chamber (TPC) for the International Linear Collider will need to measure about 200 track points with a resolution close to 100 $\mu$m. A Micro Pattern Gas Detector (MPGD) readout TPC could achieve the desired resolution with existing techniques using sub-millimeter width pads at the expense of a large increase in the detector cost and complexity. We have recently applied a new MPGD readout concept of charge dispersion to a prototype GEM-TPC and demonstrated the feasibility of achieving good resolution with pads similar in width to the ones used for the proportional wire TPC. The charge dispersion studies were repeated with a Micromegas TPC amplification stage. We present here our first results on the Micromegas-TPC resolution with charge dispersion. The TPC resolution with the Micromegas readout is compared to our earlier GEM results and to the resolution expected from electron statistics and transverse diffusion in a gaseous TPC.Comment: 5 pages, 8 figures, to appar in the Proceedings of the 2005 International Linear Collider Workshop (LCWS05), Stanford, 18-22 March 200

Spatial resolution of a GEM readout TPC using the charge dispersion signal

A large volume Time Projection Chamber (TPC) is being considered for the central charged particle tracker for the detector for the proposed International Linear Collider (ILC). To meet the ILC-TPC spatial resolution challenge of ~100 microns with a manageable number of readout pads and channels of electronics, Micro Pattern Gas Detectors (MPGD) are being developed which could use pads comparable in width to the proportional-wire/cathode-pad TPC. We have built a prototype GEM readout TPC with 2 mm x 6 mm pads using the new concept of charge dispersion in MPGDs with a resistive anode. The dependence of transverse resolution on the drift distance has been measured for small angle tracks in cosmic ray tests without a magnetic field for Ar/CO2 (90:10). The GEM-TPC resolution with charge dispersion readout is significantly better than previous measurements carried out with conventional direct charge readout techniques.Comment: 5 figures, 10 page

Performance of the TPC with Micro Pixel Chamber Readout: micro-TPC

Micro-TPC, a time projection chamber(TPC) with micro pixel chamber($\mu$-PIC) readout was developed for the detection of the three-dimensional fine(sub-m illimeter) tracks of charged particles. We developed a two-dimensional position sensitive gaseous detector, or the $\mu$-PIC, with the detection area of 10$\times$10 cm${}^{2}$ and 65536 anode electrodes of 400 $\mu$m pitch. We achieved the gas gain of over 10000 without any other multipliers. With the pipe-line readout system specially developed for the $\mu$-PIC, we detected X-rays at the rate as high as 7.7 Mcps. We attached a drift cage with an 8 cm drift length to the $\mu$-PIC and developed a micro-TPC. We measured the basic performances of the micro-TPC and took three-dimensional tracks of electrons. We also developed a prototype of the MeV gamma-ray imaging detector which is a hybrid of the micro-TPC and NaI(Tl) scintillators and confirmed its concept by reconstructing the obtained data.Comment: 6 pages 16 figures, submitted for IEEE/TNS 200

Impact of different solvents on the recovery of bioactive compounds and antioxidant properties from lemon (Citrus limon L.) pomace waste

The effects of different solvents on the recovery of (i) extractable solids (ES), (ii) total phenolic compounds (TPC), (iii) total flavonoid content (TFC), (iv) vitamin C, and (v) antioxidant activity from lemon pomace waste were investigated. The results revealed that solvents significantly affected the recovery of ES, TPC, TFC, and antioxidant properties. Absolute methanol and 50% acetone resulted in the highest extraction yields of TPC, whereas absolute methanol resulted in the highest extraction of TFC, and water had the highest recovery of vitamin C. 50% ethanol, and 50% acetone had higher extraction yields for TPC, and TFC, as well as higher antioxidant activity compared with their absolute solvents and water. TPC and TFC were shown to be the major components contributing to the antioxidant activity of lemon pomace

Comparative evaluation of phytochemical profiles and identification of flavonoids in cereal grains

The phytochemicals including flavonoids and phenolic acids mainly contained in the outer layer of the kernels are key factors responsible for the biofunctionality of whole grains. The phytochemical profiles of twelve grain samples comprising 6 wheats, 3 barleys and 3 oats were studied for comparative evaluation of their antioxidant properties. Total phenolic content (TPC) and antioxidant activities (DPPH and ORAC) of the grain extracts were measured. The bound phenolic acids were identified and quantified using HPLC and mass spectrometry. The flavonoids in different grain were analyzed using HPLC and tandem mass spectrometric techniques. TPC in acidified methanol extracts ranged from 164 to 226, 264-391, and 308-331 mg/100 g for wheat, oats and barley, respectively. Similarly TPC in acetone extracts were 78 to 118, 223 to 351 and 367 to 433 mg/100 g. Acetone extracts had significantly (p < 0.05) higher TPC than acidified methanol extracts for barley samples. On the contrary, acidified methanol extracts from wheat and oats had higher TPC than their acetone extracts. The results showed that for both acetone and acidified methanol extracts, barley samples had significantly higher antioxidant activity than oats and wheat samples although even some of the oats had similar or even higher TPC compared to barley samples. Wheat extracts had low antioxidant activity assayed using both DPPH and ORAC assays. Oats had the highest levels of bound phenolic acids (431 to 656 mg/100 g) followed by wheat samples (91 to 153 mg/100 g). The bound phenolic acid contents of barley samples ranged from 81–105 mg/100 g. The major flavonoids in barley samples are dimers and trimers of proanthocyanidins, while flavone glucosides are the major flavonoids for wheat. The phytochemical including flavonoid profile may explain the antioxidant activity for different cereal grain rather than TPC

Particle Identification Studies with an ALICE Test TPC

Using a test TPC, consisting of the ALICE TPC field cage prototype in combination with the final ALICE TPC readout and electronics, the energy loss distribution and resolution were measured for identified protons. The measurements were compared to theoretical calculations and good quantitative agreement was found when detector effects were taken into account. The implications for particle identification are discussed.Comment: 6 pages, 4 figures, Quark Matter 06 poster proceedin