Fabrication, testing and simulation of a high spatial resolution alpha-particle imager based on ZnO nanowires in a polycarbonate nanoporous membrane

A new architecture consisting of ZnO nanowires embedded in a polycarbonate nanoporous membrane was proposed, fabricated and simulated as a high spatial resolution alpha particle imager. The experimental and Geant4 simulation results showed that ZnO nanowires could act as scintillating fibers to prevent spread of the generated optical photons inside the imager. This property can be used to precisely determine alpha collision coordinates. An array of these nanowires can be also applied as a new high spatial resolution alpha particle imager

Determination of Dose-Equivalent Response of A Typical Diamond Microdosimeter in Space Radiation Fields

Introduction: Microdosimeters are helpful for dose equivalent measurement in unknown radiation fields. The favorable physical and mechanical properties of the detector-grade chemical vapor deposition diamond materials have made the diamond microdosimeters suitable candidate for radioprotection applications in space. The purpose of this work is the investigation of the dose equivalent response of a typical diamond microdosimeter with laser-induced graphitized electrodes for use in space radiation fields. Materials and Methods: The Geant4 Monte Carlo simulation toolkit was applied to simulate the particle transport within the microdosimeter, and to determine the mean chord length and the dose equivalent response of the microdosimeter, based on the lineal energy dependent quality factor.   Results: The linear stopping power of the protons and alpha particles with energies higher than 5 MeV and 10 MeV respectively can be estimated within20% of deviation using the microdosimeter response. The fluence to dose equivalent conversion coefficients calculated affirms that there is an adequate agreement between the calculated coefficients and other research group results. Conclusion: The reasonable agreement between the dose equivalents calculated in this study and the results reported by other researchers confirmed that this type of microdosimeter could be a promising candidate suitable for the measurement of the dose equivalent in space radiation fields

Modeling of an integrated active feedback preamplifier in a 025 mu m CMOS technology at cryogenic temperatures

This paper describes the modeling of a standard 0.25 mu m CMOS technology at cryogenic temperatures. In the first step of the work, the parameters of the EKV v2.6 model were extracted at different temperatures (300, 150, and 70 K). The extracted parameters were then used to optimize the performance of a room temperature designed active feedback front-end preamplifier (AFP) at 130 K. The results show that with a small adjustment of the extracted parameters it is possible to have a reasonable model at low temperatures. By optimizing the bias conditions at 130 K, a fall time down to 1.5 ns and a double pulse resolution of 6.5 ns were measured for NA60 proton beamscope. The proposed approach will also allow a low temperature design optimization for future projects, which will not be possible using only standard models provided by the foundry. (16 refs)

A high-speed low-noise transimpedance amplifier in a 025 mum CMOS technology

We present the simulated and measured performance of a transimpedance amplifier designed in a quarter micron CMOS process. Containing only NMOS and PMOS devices, this amplifier can be integrated in any submicron CMOS process. The main feature of this design is the use of a transistor in the feedback path instead of a resistor. The circuit has been optimized for reading signals coming from silicon strip detectors with few pF input capacitance. For an input charge of 4fC, an input capacitance of 4pF and a transresistance of 135kOmega, we have measured an output pulse fall time of 3ns and an Equivalent Noise Charge (ENC) of around 350 electrons rms. In view of the operation of the chip at cryogenic temperatures, measurements at 130K have also been carried out, showing an overall improvement in the performance of the chip. Fall times down to 1.5ns have been measured. An integrated circuit containing 32 channels has been designed and wire bonded to a silicon strip detector and successfully used for the construction of a high-intensity proton beam hodoscope for the NA60 experiment. The chip has been laid out using special techniques to improve its radiation tolerance, and it has been irradiated up to 10Mrd (SiO//2) without any degradation in the performance