Study On Key Technology Of Novel Pulsed Gamma-ray Detection Methods

The temporal profile detection of pulsed gamma-rays is one of the most important neaclear raididation diagnoses,which characterizes the time performance and dynamic process of a pulsed radiation source.Such as Laser Interial Confinement Fusion(ICF)facility?Free Electron Laser(FEL)?Synchrotron Radiation Source?Inverse Compton Scattering Gamma-ray Source and Laser Driven Radiation Source are ultrafast pulsed gamma-ray sources,of which detection systems time resolution must be in the scale of 100ps or ps.Due to space charge limitations and low-bandwidth of coaxial cables,the temporal response of state-of-the-art electronic detection systems is hardly down to 100ps Therefore,converting pulsed gamma rays to light is the only feasible way to develop the novel ultrafast pulsed gamma-ray detection methods.In this paper,the novel methods about pulsed gamma-ray temporal profile have been systematically explored and studyed to meet the aim of ultrafast pulsed radiation field diagnosis.The main content covers some key parts such as new detection theory?feasibility analysis?technical routes design and realization?main physical quantity evaluation and novel application of the methods.CH3NH3PbC13 and its halide-doped crystals have been firstly applied for the temporal profile diagnosis of ultrafast pulsed gamma-ray with deeply investigating their scintillation features beforehand.Large-size and good-transparency CH3NH3PbCl3 samples have been prepared and characterized by modificated technological parameters.Their different optical spectrums are acquired in the conditions of room temperature and liquid helium temperature.The ultrafast scintillation property of the samples is discovered through the single photon counting method under different temperature conditions.And the rising edges of the scintillation time are less than 100ps.A scintillation detection system with the function of fluorescence time delay is designed and established according to the image transfer principle.Pulsed laser and pulsed gamma ray with ps duration are employed to investigate the time response performance.Rising edge of 458.7ps and FWHM(full width of half maximum)of 710ps are acqiuired in the experoiments.The results also indicate that the detection system can achieve a timescale of less than 100ps by using streak camera to record the light pulse.A new class of ultrafast pulsed gamma ray detection methed by sensing carrier changes in a diode laser cavity has been firstly proposed and investigated,which has achieved the signal conversion from pulsed gamma ray to coherent light with high fidelity.In theory,residual free carrier density in the active region induced by gamma rays are calculated with Monte Carlo computational methods.And the relationship between the free carrier density and laser power is derived from carrier rate equation.A general expression of gamma-ray sensitivity has derived and used to evaluate the instrinsic sensitivity(6.72×10-21C·cm2).The time scale of about 10ps response is analysed with both rate equation and Monte Carlo methods.A prototype detection system is established with an AlGaInP/GaInP multiple quantum well laser,which has been used to demonstrate the feasibility of temporal profile measurement.The relative sensitivity of the prototype system is estimated at about 1.27×10-18C·cm2 by the results of the experiments at the accelerator named "Qiangguang-I".The experimental behaviors generally agree with the characterizations of theoretical analysis.Because of response bandwidth limitation,the evaluated results can't show the system's actual response time.A novel class of pulsed gamma ray detection methed based on laser polarization modulation has been firstly presented and demonstrated,which roots in the instantaneous radiation effect of semiconductor refractive index and optical Fresnel formula.According to the mechanism of interaction between pulsed gamma-ray and semiconductor,the relationships among gamma rays?free carriers and refractive index change have been analysized to get the function expression between refractive index change and laser polarization amplitude.A general sensitivity expression is given via Fresnel formula.A prototype detection system is developed with a He-Ne laser,both the transmissivity of vertical polarization and the reflectivity of horizontal polarization are employed as the armed probe to validate the method's feasibility.And then,a intracavity modulation conceptual system has also designed and realized with a Nd:YAG solid laser,which is used to investigate the propability and specialty of measuring pulsed gamma-ray temporal profile.Its relative sensitivity is estimated as about 5.34×10-17C·cm2 from the experiment results,which is large enough to achieve low-intensity pulsed gamma-ray detection.Lastly,laser-X-ray cooperative communication technology,as a novel means of communication,has been developed for the first time,which is a new application of the"Rad-Optic" dection method.We have analyzed and dicussed the principle?the main constitution and the key technical segments of the cooperative communication system.And necessary experiment research has been carried out to solve these key problems.A high repetition frequency pulsed X-ray source is developed on the stage of the photocathode DC electron gun,with a repetition frequency of 2MHz?a charge quantity of 50pC and a focus diameter of 2mm.W target is designed to get pulsed X-ray with low energy less than 100keV.Moreover,a prototype system of laser-X-ray cooperative communication is developed and its exploratory experiment is finished with the aid of the scintillation detection system based on perovskite crystal,which shows the general way of signal communication with this technology.In this paper,we have firstly proposed and investigated three novel kinds of pulsed gamma-ray temporal profile detection method,including two signal conversion paths of"Rad-fluorescent light" and "Rad-coherent light".The conclusion indicates that all the three methods can achieve the aim of detecting gamma-ray temporal profile.And the corresponding detection system will probably achieved the aim of measuring the temporal profile of ultrafast pulsed gamma ray source such as ICF fusion facility and Thomson Scattering source.And laser-X-ray cooperative communication technology will be used in some special communication links.For example,it can be used as a kind of space cooperative privacy communication technology.We believe laser-X-ray cooperative communication technology will provide a favourable complement for the wireless communication field.