Performance study of a micro-pattern gas detector: leak microstructure

A micro-pattern gas detector named leak microstructure （LM） has been studied. A new chemical electrolytic technique is introduced to make perfect shaped LM needles with very sharp tips, and this method may be developed to make LM array detectors in batches. The experimental results are presented for both a single needle LM detector and a small LM array detector. The gas gain is up to 105 by calculation from the waveform. Good gain stability and uniformity are achieved. The light emission from the needle tip is also measured in Ar/CF4 （95/5） gas mixture. The result shows a promising application for imaging.

Study of a bulk-Micromegas with a resistive anode

The design and performance of a Micromegas with a resistive anode are presented in this paper. A thin resistive sheet with volume resistivity of 10^12 Ω·cm is glued onto the readout electrode surface and its performance is investigated by using a 55Fe X-ray radioactive source in the operation gas of argon and isobutene mixtures （Ar/Iso=95/5）. The gas gain at different mesh high voltage, counting rate and working time are given. Energy spectra at different working voltages are measured and the results are discussed. We have oberved that a Micromegas with a resistive anode can be operated at higer gain than a standard Micromegas without sparks.

Experimental studies of THGEM in different Ar/CO_2 mixtures

In this paper, the performance of a type of domestic THGEM （THick Gaseous Electron Multiplier） working in Ar/CO2 mixtures is reported in detail. This kind of single THGEM can provide a gain range from 100 to 1000, which is very suitable for application in neutron detection. In order to study its basic characteristics as a reference for the development of a THGEM based neutron detector, the counting rate plateau, the energy resolution and the gain of the THGEM have been measured in different Ar/CO2 mixtures with a variety of electrical fields. For the Ar/CO2（90%/10%） gas mixture, a wide counting rate plateau is achieved from 720 V to 770 V, with a plateau slope of 2.4%/100 V, and an excellent energy resolution of about 22% is obtained at the 5.9 keV full energy peak of the 55Fe X-ray source.

A large-area GEM detector using a novel self-stretching technique

A Gas Electron Multiplier （GEM） detector with an effective area of 300 mm×300 mm has been constructed using a novel self-stretching technique, which allows a highly flexible and efficient GEM detector assembly free of glue or spacers. This makes the re-opening and repair of the GEM detectors possible and significantly reduces the scrap rate in the mass production of large-area GEM detectors. With the technique, the assembly time can be limited to a few hours, a factor of ten improvement compared to that using gluing techniques. The details of design and assembly procedure of the 300 mm×300 mm GEM detector are described in this paper. This detector was tested with 8 keV X-rays for the effective gain, energy resolution and performance uniformity. The results show that the typical energy resolution is 20% at an effective gain of about 10-4, with fairly good uniformity.

Experimental study of a THGEM detector with mini-rims

The gas gain and energy resolution of single and double THGEM detectors （5 cm×5 cm effective area） with mini-rims （rim less than 10 um） were studied. The maximum gain was found to reach 5×103 and 2 × 105 for single and double THGEMs respectively, while the energy resolution for 5.9 keV X-rays varied from 18% to 28% for both single and double THGEM detectors of different hole sizes and thicknesses. Different combinations were also investigated of noble gases （argon, neon） mixed with a quantity of other gases （isobutane, methane） at atmospheric pressure.