In the highly sensitive detection field, charge-sensitive amplifier is widely used in the preamplifier of detectors, however, the high voltage applied to these detectors (such as CZT nuclear detector) often make serious noise, which may influence the sensitivity of the detector. Despite the traditional passive filter circuit to eliminate the noise of the power, but if the power supply accuracy isn’t high enough and the passive circuit eliminate the power supply noise is incomplete. The noise still may affect the performance of the final system. According to the need of nuclear detection and photoelectric detection, a kind of differential JFET charge-sensitive preamplifier is proposed in this paper, which eliminates the power-supply noise and Johnson noise of bias resistance. First, theoretical analysis of the traditional JFET circuit is proved and simulation of the JFET circuit is performed with ORCAD software, which prove that power-supply noise effect the preamplifier. Next, simulation of the innovative circuit is performed with ORCAD software. Finally, the fabricated circuit board is tested with avalanche photo diode (APD). It is shown that the charge-sensitive preamplifier with differential JFET input can significantly eliminate the power-supply noise and Johnson noise of resistance (both low frequency and high frequency) and realize a high sensitivity.
Transient x-ray diffraction, also called time-resolved x-ray diffraction and dynamic x-ray diffraction, is one novel diagnostic technique for probing shocked solids. It can provide direct information about microscopic mechanisms governing shock-induced deformation and structural changes at atomistic scales with nanosecond and picoseconds resolution, and lately, it has become possible to measure the structure of transients with sub-picoseconds and sub–Angstrom resolution with the development of ultrafast lasers which can produce femtosecond electron and x-ray pulses in the form of characteristics emission lines as well as x-ray continua in the keV range. In this paper, we detect and measure directly the dynamic response of lithium fluoride single crystal shocked compressed by laser irradiation in SHENGUANG II. In our experiments, high-intensity lasers irradiated a thin Cu foil to generate helium-like rays as x-ray source. Film (IP--image plate) recorded x rays diffracted from multiple lattice planes both perpendicular and oblique angles to the shock loading direction . We gained the diffraction signals of the lattice planes (200) shocked and unshocked, what’s more, other lattices (113), (1-13). The positions of the diffraction lines associated with the (200) lattice plane indicated compression of the lattice along  direction by 13%. In the experiment, a large-angle detector consists of two films-one rectangular in shape,one triangular in shape that are positioned to record x rays diffracted from a shocked single crystal nearly within a full π steradian. The experiment shows that transient x-ray diffraction can diagnose the dynamical response of solid with higher resolution.
X-ray spectrograph has long been used as a means of diagnosing conditions of laser-produced plasmas, as information concerning both the temperature and density can be extracted from the emitted radiation. For the measurement of X-ray lines in the energy range of 0.6-6 keV, A curved crystal X-ray spectrometer of reflection type elliptical geometry is required. In order to obtain both high resolution and collection efficiency the elliptical geometry is more advantageous than the flat configurations. Elliptical curved crystals spectrograph with a relatively wide spectral range are of particular use for deducing electron temperatures by measurement of the ratios of lines associated with different charge states. Curved crystals analyzer was designed and manufactured for use on an experiment to investigate the properties of laser produced plasmas. The spectrograph has 1350mm focal length and for these measurements, utilized PET, LIF, KAP and MICA crystal bent onto an elliptical substrate. This crystal analyzer covers the Bragg angel range from 30 to 67.5. The analyzer based on elliptically geometrical principle, which has self-focusing characteristics. The experiment was carried out on Shanghai Shengguang-II Facility and aimed to investigate the characteristics of a high density plasma. Experimental results using Curved crystal analyzer are described which show spectrum of Ti, Au laser-plasma. The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal. Spectra showing the main resonance
line were recorded with X-ray CCD and with laser energies 150J laser wavelength 350nm. The calculated wavelength resolution is about 500-1000.
A new crystal spectrometer has been designed and fabricated for measuring laser-plasma x-ray in the 0.99-1.83-nm region. The cleaved mica crystal with 0.2-mm thickness was curved and glued on an elliptical substrate as the dispersive element. The x-ray source and exit slit are respectively placed at the first and second focal point of the elliptical crystal. The x-ray is diffracted by the mica crystal and focused at the exit slit. An x-ray sensitive charge coupled device or streak camera can be easily amounted in the perpendicular orientation to record the space and time resolved x-ray spectra. The spectrometer was tested at the XG-2 laser facility, and the experimental result shows that the maximum spectral resolution is 999.
In order to measure laser-produced plasma x-ray in the 1.33-2.46-nm region, an elliptical crystal spectrograph has been designed and fabricated. The potassium acid phthalate (KAP) crystal with a 2d spacing of 2.663 nm is used as the x-ray dispersive element, it is elliptically bent and glued on a rustless-steel substrate with a 0.9586 eccentricity and a 1350-mm focal distance. The spectrograph is equipped with an x-ray charge-coupled device (CCD) camera for recording the space-resolved spectrum on one port, and an x-ray streak camera for recording the time-resolved spectrum on another port. The first testing experiment was carried out on the XG-2 target chamber, the experimental results demonstrate that the spectral resolution is about 640 for this spectrograph.
A novel elliptical crystal spectrometer has been designed and manufactured to diagnose pulsed plasmas x-ray. The light path is designed according to the elliptical focusing property. The spectrometer is composed of the elliptical x-ray analyzer, the alignment devices, the vacuum system, the ports of the spectral detectors for x-ray CCD camera and x-ray streak camara, the supporting base, and the adapting flange to the target chamber. The target-shooting experiment was performed at the XG-Π and SGΠlaser facilities for testing the spectrometer. The optical system, optoelectronic machinery system, experimental results are discussed in this paper.