4865 results about "Nuclear engineering" patented technology

A nuclear fusion reaction device, system and method. The outer wall of a vacuum chamber (301) in the nuclear fusion reaction device (30) comprises an inner ring surface (M1) and an outer ring surface (M2) which are connected to each other; the outer ring surface (M2) surrounds the inner ring surface (M1); the inner ring surface (M1) protrudes toward the central axis of the vacuum chamber (301); the vacuum chamber (301) surrounds a plurality of first coils (302); at least some of the plurality of first coils (302) extend in the circumferential direction of the inner ring surface (M1) and are sequentially arranged in the axial direction of the vacuum chamber (301); a plurality of second coils (303) surround the vacuum chamber (301), extend in the circumferential direction of the outer ring surface (M2), and are sequentially arranged in the axial direction of the vacuum chamber (301); a plurality of third coils (304) all surround the vacuum chamber (301) and are sequentially arranged in the circumferential direction of the vacuum chamber (301); and the plurality of first coils (302), the plurality of second coils (303), and the plurality of third coils (304) are used for generating a magnetic field, such that plasma rings with negative triangular deformation are generated in the vacuum chamber (301), and a fusion reaction occurs.

The invention relates to the technical field of nuclear fusion devices, and discloses a nuclear fusion device and a monitoring system and an installation method thereof, the monitoring system comprises a cold shield main body, the cold shield main body is of an annular rotation structure, and the cold shield main body is arranged in a cavity and wraps the circumferential outer side of a vacuum chamber; the cold shield main body comprises a plurality of groups of fan-shaped cold shield sections which are sequentially arranged in the circumferential direction, and the plurality of groups of fan-shaped cold shield sections are encircled to form the cold shield main body; the distance measuring assembly is arranged on the cold shield main body, the distance measuring assembly comprises a plurality of groups of distance measuring sensors which are arranged in the circumferential direction of the cold shield main body at intervals, and each group of distance measuring sensors comprises a plurality of distance measuring sensors; the distance measuring sensor is used for detecting the size of a gap between the cold shield body and the longitudinal field coil and the size of a gap between the cold shield body and the vacuum chamber. Therefore, the cold shield main body can be assisted to be assembled at a position in the nuclear fusion device, and the matching position of the cold shield main body, the vacuum chamber and the longitudinal field coil can be monitored in real time.

The invention relates to the field of medical equipment, and provides a compact multi-chamber proton treatment system based on a shared beam line, and the system comprises a fixed beam transmission line which is used for guiding the movement direction of a proton beam into a vertical direction; the rotating beam transmission line is used for guiding the movement direction of the proton beam into the horizontal direction; one end of the fixed beam transmission line is connected with the proton cyclotron, the other end of the fixed beam transmission line is connected with one end of the rotary beam transmission line, and the other end of the rotary beam transmission line is in butt joint with a plurality of treatment rooms; the rotating beam transmission line rotates around a central axis extending in the vertical direction. According to the invention, the proton beam can be safely, efficiently and accurately transmitted to each treatment room, and a fixed beam transmission system and a rotating rack do not need to be independently arranged for each treatment room, so that the beam control assembly and the system occupied area of the multi-room particle treatment device are minimized, and the number of treated patients can be remarkably increased.

The invention discloses a processing method of a fusion device, and belongs to the technical field of nuclear fusion. The processing method comprises the following steps: carrying out at least one time of vacuum heat treatment on a Dewar embedded part blank; carrying out cleaning anti-corrosion treatment and physical correction treatment on the surface of the dewar embedded part blank subjected to heat treatment; carrying out grinding and polishing treatment on the surface of the Dewar embedded part blank subjected to the cleaning and antiseptic treatment and the physical correction treatment to obtain the Dewar embedded part; the Dewar embedded part is transported to the installation position of the window to be installed, and the Dewar embedded part located at the installation position is temporarily fixed; performing concrete pouring on the mounting position of the Dewar embedded part; and after the concrete is solidified, a cast-in-place concrete structural body is formed in the area below the Dewar embedded part, and a part of the Dewar embedded part is embedded into the cast-in-place concrete structural body. By means of the method, the magnetic conductivity of the Dewar embedded part is reduced, and the risk that elements are activated to form isotopes with the long decay period and the high irradiation dose rate or isotopes with the short decay period and the high irradiation dose rate is reduced.

The utility model relates to the technical field of electron beam transmission, in particular to a magnet system. Comprising a first shaping unit and a second shaping unit, and the first shaping unit comprises first quadrupole iron tightly attached to an outlet of the accelerating tube and first octupole iron arranged at the focus position of the first quadrupole iron; the second shaping unit comprises second quadrupole iron and second octupole iron, the second quadrupole iron and the first octupole iron meet a first preset distance, the second octupole iron is arranged at the focus position of the second quadrupole iron, and the second shaping unit and the radiation field area meet a second preset distance; the inner diameter of the first octupole iron and the inner diameter of the second octupole iron are both larger than or equal to the maximum size of an electron beam group. Therefore, the quadrupole iron and the octupole iron are utilized to form the shaping unit which is homogenized in one direction, so that the problems that in the prior art, in the electron beam transmission process, a large amount of dose is lost, the size of a radiation field is limited, and the radiation field cannot be adjusted at will are solved; therefore, the electron beam bunch generated by the linear accelerator can be expanded and homogenized in a short distance.

A positron emission tomography (PET) scanner includes a plurality of gamma radiation detector modules arranged to form a detector ring. Each detector module includes an array of scintillator detectors. Each scintillator detector comprises a monolithic scintillation crystal and a plurality of photodetector arrays, such as silicon photomultipliers (SiPMs). A photodetector array is positioned on at least two nonparallel faces of each scintillation crystal. In some examples, a photodetector array is positioned on each of three orthogonal faces of each scintillation crystal.

The invention discloses a method and tool for manufacturing a cold shield of a nuclear fusion device, and relates to the technical field of metal plate machining. The manufacturing method of the cold shield of the nuclear fusion device comprises the following steps: providing a sub-panel, a flange and a pipe fitting; the multiple sub-panels are welded, and a first middleware is obtained; welding the edge of the first middleware and the turnup to obtain a second middleware; after the pipe fitting is welded to the surface of the second middleware, a third middleware is obtained; and the third middleware is shaped. According to the method, the third middleware is shaped, that is, the third middleware is shaped after all welding procedures are completed, so that the third middleware has relatively small profile tolerance, the profile tolerance of the cold shield meets the design requirement, the assembly difficulty of the cold shield is reduced, and the risk of failure of the cold shield is reduced.

The invention discloses an ocean in-situ radioactivity monitoring method, which is characterized in that feature extraction is carried out based on a maximum likelihood expected value maximization (MLEM) algorithm, and spectrum unfolding operation is carried out by adopting a multi-layer perceptron. The method comprises the following steps: firstly, measuring FWHM related parameters of a CeBr3 detector by adopting a standard source, simulating the response of the detector to gamma rays in a marine environment based on a Monte Carlo method, and establishing a full-spectrum response matrix H in a range of 0-2048keV; based on the response matrix H, reconstructing a gamma energy spectrum y obtained by the detector by using an MLEM iterative algorithm; and the reconstructed spectrum is used as the input of a multi-layer perceptron (MLP), and qualitative and quantitative analysis of radionuclides in the energy spectrum is realized. According to the method, the discrete characteristic peak signal is convolved into the single path address corresponding to the characteristic energy, so that the accuracy of the MLP model in the spectrum unfolding process is effectively improved.

The invention provides a device and method for removing aerosol based on a charged spraying coupling pool washing mechanism, and belongs to the field of nuclear auxiliary systems. The problem that radioactive aerosol particles generated when a radioactive contamination structure in a reactor is cut underwater can be released into the external environment is solved. Wherein the underwater laser cutting assembly is used for cutting a to-be-cut piece; the auxiliary gas chamber is communicated with the laser cutting nozzle; the aerosol charging assembly can enable aerosol particles generated by underwater laser cutting to carry negative charges; the baffle can gather the aerosol particles and guide the aerosol particles to the aerosol charging assembly; the liquid drop charged spraying assembly can spray liquid drops carrying positive charges, the liquid drops carrying positive charges and aerosol particles carrying negative charges can attract each other and fall to the liquid level, and the Venturi washing assembly can extract gas above the liquid level and spray the gas below the liquid level. The device can efficiently remove radioactive aerosol particles generated by cutting and disassembling radioactive contaminated components in a nuclear power plant, and radioactive contamination to the environment is prevented.

The invention discloses a BNCT dose calculation method, which comprises the following steps: S1, constructing a voxel model, initializing one or more particles in a simulation system, and respectively acquiring the initial position, energy and movement direction of each particle; s2, adaptively selecting a Monte Carlo particle tracking algorithm and a flux counting mode based on the region where the particles are located and the energy of the particles; s3, repeating the step S2 until the particles leave the simulation system or are killed when meeting a truncation condition; and S4, cumulatively calculating dose distribution. Through the BNCT dose calculation method, the Monte Carlo particle transport simulation time is greatly shortened, the BNCT dose calculation efficiency is optimized, and the method is suitable for rapid and high-precision radiation dose simulation under a BNCT complex tissue structure.

The invention relates to the technical field of gamma-ray spectrum analysis, particularly provides a gamma-ray detector activation analysis method and a PGNAA detection system, and aims to solve the problems that gamma rays obtained by detection of an existing gamma-ray detector comprise rays generated by decay of crystals after activation in a neutron field; therefore, the component detection result of the to-be-detected sample is not accurate. In order to achieve the purpose, the activation analysis method for the gamma detector comprises the steps that a to-be-detected sample is irradiated through a neutron source; repeatedly collecting a plurality of groups of gamma-ray energy spectrums of the sample to be detected by using a gamma-ray detector; constructing an energy spectrum signal matrix based on the gamma-ray energy spectrum of the to-be-detected sample, wherein the energy spectrum signal matrix is a mixed signal composed of instant gamma rays generated by neutron activation of the to-be-detected sample, environmental background gamma rays and interference signals generated by crystal activation in a gamma detector; and obtaining the effective instant gamma ray based on the energy spectrum signal matrix. The self-interference influence of the detector is effectively reduced, and the target element content evaluation precision of the to-be-detected object is improved.

The invention relates to the technical field of Tokamak nuclear fusion, and discloses an assembling method of a pre-assembled assembly of a nuclear fusion device and an installing method of the nuclear fusion device. The pre-assembled assembly comprises a vacuum chamber, a window neck tube in the vacuum chamber, a vacuum chamber cold shield and a TF magnet; the assembling method of the nuclear fusion device preassembled assembly comprises the following steps: supporting between a cold shield inner sector and a vacuum chamber through a first tool; a first tool is supported between the cold shield outer sector and the vacuum chamber; the TF magnet is connected with the middle window position of the vacuum chamber through a second tool, the upper arc-shaped section of the outer fan section of the cold shield is connected with the hoisting tool of the TF magnet through a third tool, and the lower window section of the outer fan section of the cold shield is connected with the second tool; and the middle window section and the annular field magnet supporting seat are connected through a fourth tool. According to the assembling method of the nuclear fusion device pre-assembled assembly, interference among installation of the vacuum chamber, the window neck tube in the vacuum chamber, the vacuum chamber cold shield and the TF magnet can be avoided, and the stability and functionality of the pre-assembled assembly structure are guaranteed.

A cooling system for vehicles and a control method thereof improves indoor heating performance and fuel efficiency by controlling a flow rate of a coolant passing through a heater core together with an EGR cooler. A coolant having an increased temperature is first supplied to the heater core side through a flow stagnancy control to rapidly increase the temperature of the coolant flowing in the heater core, thereby improving heating performance. A warm-up feature is improved through an exhaust heat recovery function by a heat exchange between the exhaust gas and the coolant in the EGR cooler, thereby improving efficiency of fuel.

The invention relates to a containment pressure suppression, filtration and discharge system and method and application thereof, and belongs to the field of special safety facilities and radiation protection of nuclear power devices. The containment pressure suppression, filtration and discharge system comprises a discharge valve (2), a discharge pipeline (3), a spray pipe (4), a pressure suppression pool, an expansion chamber (7), a steam-water separator (9), a metal fiber filter layer (10), a rupture disk (12), a heat exchanger and a valve. According to the containment pressure suppression filtering and discharging system, the seawater side heat exchanger and the pressure suppression pool heat exchanger are arranged, and a natural circulation loop is constructed by means of the potential difference between the seawater side heat exchanger and the pressure suppression pool heat exchanger and the temperature difference between seawater and a liquid phase in a pressure suppression pool under the accident condition; the heat of the suppression pool can be guided out without time limit under the condition of an LOCA accident or a main steam pipeline fracture accident in the containment; by adopting a pressure suppression washing method with multi-stage bubbling, rapid pressure suppression of the containment and efficient retention of airborne radioactive substances can be realized; occupation of total resources is reduced by arranging the combined metal fiber filter layer.

A structure and process for containing a nuclear reaction is disclosed. The structure and process may involve a nuclear containment structure including a plurality of metallic rings stacked axially to form the nuclear containment structure, the nuclear containment structure being configured to: mitigate, by using a physical barrier, the movement of radionuclides from inside a containment structure to a surrounding space; shield, by varying the alloy properties throughout the containment structure, an exterior of the containment structure from radiation produced inside of the containment structure; regulate, by transferring thermal energy, a temperature within the containment structure; regulate, by storing thermal energy, the temperature within the containment structure; shield, components within the nuclear containment structure from kinetic events external to the nuclear containment structure; and shield, the external environment, from kinetic events within the nuclear containment structure.

The invention provides a liquid cooling impurity monitoring method and system, and the method comprises the steps: obtaining an existing liquid cooling impurity attribute set through spectral analysis and microscopic imaging, deploying an impurity detection module in a liquid cooling channel, and obtaining a resonance spectrogram of the liquid cooling channel and environment parameters of the liquid cooling channel; performing cooperative feature extraction on the liquid-cooling cold channel resonance spectrogram and the liquid-cooling cold channel environment data, generating a liquid-cooling ecological vector, obtaining a historical liquid-cooling ecological vector corresponding to the historical data of the liquid-cooling cold channel, constructing a liquid-cooling impurity monitoring model, performing model pre-training to generate a liquid-cooling impurity library, inputting the liquid-cooling ecological vector to the liquid-cooling impurity monitoring model, and obtaining a liquid-cooling impurity monitoring result. Performing liquid cooling impurity matching on the liquid cooling ecological vector and a liquid cooling impurity library based on a cuckoo algorithm to obtain a liquid cooling impurity combination vector, obtaining a pre-trained impurity purification decision model, inputting the liquid cooling impurity combination vector into the impurity purification decision model, and generating an optimal liquid cooling impurity purification strategy, and a user can perform impurity removal on the liquid cooling system according to the optimal liquid cooling purification strategy.

An electrically inactive betavoltaic battery, an electrically active betavoltaic battery, and methods of making the same are provided. In implementations, a method of making an electrically active betavoltaic battery includes: providing an electrically inactive betavoltaic battery device having one or more diodes incorporating a semiconductor material layer having a stable non-radioactive isotope; and irradiating the electrically inactive betavoltaic battery device with thermal neutrons, thereby causing the conversion of at least a portion of the stable non-radioactive isotope to a radionuclide and creating the electrically active betavoltaic battery, wherein the semiconductor material layer acts as both an electron emitter and an electron absorber simultaneously.

A radiation imaging system comprises a sensor unit of a radiation imaging device, detecting an incident radiation R irradiated from a radiation generator; an arithmetic unit calculating an accumulated dose of the radiation detected by the sensor unit; and an imaging control unit outputting an irradiation stop signal for stopping the irradiation of the radiation R to the radiation generator when the accumulated dose reaches a threshold or more, wherein the imaging control unit sets the threshold based on a dose rate of the radiation R determined based on a relationship between the accumulated dose and a time, and a delay time from a time of outputting the irradiation stop signal to a time of stopping the irradiation of the radiation of the radiation generator.

A positron emission tomography (PET) scanner includes a plurality of gamma radiation detector modules arranged to form a detector ring. Each detector module includes an array of scintillator detectors. Each scintillator detector comprises a monolithic scintillation crystal and a plurality of photodetector arrays, such as silicon photomultipliers (SiPMs). A photodetector array is positioned on at least two nonparallel faces of each scintillation crystal. In some examples, a photodetector array is positioned on each of three orthogonal faces of each scintillation crystal.

To study a system that transmutes atomic nuclei using muons, devise a light source device and a propulsion device including a nuclear transmutation system, and examine a centrifugal force application unit which may be accelerated by the propulsion device, and devise an electric field generator or a magnetic field generator.SOLUTION: A system is devised that decelerates cosmic muons produced from cosmic rays or high-speed muons derived from mesons produced from atomic collisions with electric field and deceleration means and uses the muons for nuclear transmutation. Also, a decelerator using a laser wake field and a decelerator using an element forming an electric field are proposed. A radiation light source having the nuclear transmutation unit is disclosed. An ionization device, a centrifugal gun device, a centrifugal force and pressure applying device, a pressure generation unit, a pressure applying material, a high-pressure induction superconductivity experimenting system, a magnetic device, and a magnetic sail are disclosed.SELECTED DRAWING: Figure 18

The invention discloses an element analysis device based on a high-yield DD neutron generator. The device is composed of a neutron source item system, a neutron shielding collimation wall, a detector shielding protection system, a detected sample system, a signal acquisition system and a data analysis system. A neutron beam is generated through (D, D) nuclear reaction and irradiates a sample after passing through a neutron moderation layer and a shielding collimation wall, so that the sample generates instant characteristic gamma rays. A shielding protection system with unique design effectively reduces background gamma ray interference and electromagnetic interference, and ensures that the detector accurately collects sample signals. By matching with an advanced signal acquisition and analysis system, the element components and content of the sample can be analyzed at high precision. In addition, the device can be combined with a neutron imaging system to obtain sample structure information. The method has great application potential in the fields of industrial production, scientific research and detection and the like, and can meet the requirements of high-precision element analysis on small-size samples.

The invention relates to the technical field of CLYC neutron-gamma rays, and provides a CLYC neutron-gamma ray screening detection method and device based on deep learning, and the method comprises the steps: carrying out the preprocessing of an original pulse waveform outputted by a CLYC detector, and obtaining clean standard waveform data; constructing a one-dimensional convolutional neural network model, respectively capturing the features of the waveform at different time scales, and identifying the most discriminative feature region in the waveform through an attention mechanism; performing adaptive adjustment on the original hyper-parameter of the one-dimensional convolutional neural network model to obtain an optimized hyper-parameter; establishing a direct mapping relation from an original pulse waveform to a neutron-gamma particle type to obtain a trained model; and carrying out compression optimization processing on the model, and deploying the model to an embedded platform to carry out neutron-gamma ray discrimination. According to the method, automatic extraction of deep discrimination features of the CLYC pulse waveform and accurate identification of key feature areas are realized, and the discrimination accuracy and noise interference resistance of neutron-gamma rays are improved.

Main characteristic of the invention is the exploitation of the very large flux of high energy neutrons generated in a nuclear fusion tokamak with beam-driven plasma for the purpose of producing radioisotopes. It specifically relates to the deployment of precursor materials into the core of a nuclear fusion tokamak with beam-driven plasma for the purpose of exposing these materials to the neutron flux generated in the plasma by the process of nuclear fusion of Deuterium (D) and Tritium (T) to generate radioactive isotopes, so-called radioisotopes. The precursor materials contained in metallic capsules are incorporated into the blankets that surround the plasma.

The invention discloses an ion source automatic beam adjusting method, a radiotherapy system and related equipment, and relates to the technical field of radiotherapy, and the method comprises the steps: monitoring and adjusting a plurality of control parameters in real time, and obtaining an optimal control parameter combination; under the optimal control parameter combination, the variable quantity of each control parameter before and after adjustment and the performance change of the proton beam are obtained; performing a pulse width charge test according to the variation of each parameter before and after adjustment and the performance change of the proton beam; obtaining an optimal adjustment parameter and an adjustment amount through a pulse width charge test result; and through the optimal adjustment parameter and adjustment amount, automatic beam adjustment is realized, stable and efficient acceleration of the proton beam in the synchrocyclotron system is realized, and the stability and consistency of the proton beam are ensured.

The invention discloses a hybrid neutron gamma detector array and a signal processing method, and relates to the technical field of nuclear physical detection.During detection, eight EJ200 scintillators arranged in an array are used for energy deposition of gamma rays and fast neutrons and generating photons, and meanwhile three EJ426 thermal neutron scintillation screens are used for capturing thermal neutrons and generating photons; the response of gamma rays, fast neutrons and thermal neutrons is realized at the same time, and the detection precision is greatly improved. Meanwhile, if the three EJ426 thermal neutron scintillation screens are alternately stacked front and back, the total reflection of the EJ200 scintillators and the semi-light-proof performance of the EJ426 thermal neutron scintillation screens are utilized to block photon propagation in the X direction and only enable photons to be propagated in the Y direction and the Z direction, and each EJ200 scintillator corresponds to a four-channel photon collection structure to perform high-efficiency collection of the photons, so that the high-efficiency collection of the photons is realized. Therefore, high-precision detection and high-efficiency photon collection are realized, and support is provided for subsequent intense radiation field monitoring or high-precision positioning.

The invention discloses a positive pressure antifouling gamma-ray spectrum automatic monitoring square cabin, and relates to the technical field of nuclear emergency monitoring and square cabins, the positive pressure antifouling gamma-ray spectrum automatic monitoring square cabin comprises a cabin body, a transition cabin is arranged in the cabin body, the transition cabin divides the interior of the cabin body into a sealed measurement cabin and a sample preparation cabin, and one side of the transition cabin is provided with an air-tight door capable of communicating the sealed measurement cabin with the sample preparation cabin; a sample conveying cabin used for allowing a sample to go in and out of the sealed measuring cabin and the sample preparation cabin is arranged on the side, away from the airtight door, of the inner wall of the transition cabin, the cabin body is overall designed into three areas, and the to-be-detected sample treatment area and the electric refrigeration high-purity germanium gamma-ray energy spectrometer are effectively isolated; filtered clean air is continuously introduced into the measurement cabin, the pressure in the sealed measurement cabin is maintained to be greater than the external pressure, the requirements of air cleanliness and positive pressure are ensured, and the background of the surrounding environment of the electric refrigeration high-purity germanium gamma-ray energy spectrometer is prevented from being changed after external radioactive pollution air enters the sealed measurement cabin, so that the measurement is prevented from being influenced.

A neutron capture therapy system includes a neutron generating device and a beam shaping assembly. The neutron capture therapy system further includes a concrete wall accommodating the neutron generating device and the beam shaping assembly and shielding radiations generated by the neutron generating device and the beam shaping assembly, the concrete wall and a reinforcing portion at least partially disposed in the concrete wall are provided to support the beam shaping assembly, and more than 90% of weight of a material of the reinforcing portion is composed of at least one element of C, H, O, N, Si, Al, Mg, Li, B, Mn, Cu, Zn, S, Ca, and Ti. In the neutron capture therapy system, the reinforcing portion disposed in the concrete wall has good anti-activation performance. Therefore, compared with a conventional reinforced concrete structure, the radiation is further attenuated.

A superconducting proton cyclotron (100). The superconducting proton cyclotron (100) comprises a main cyclotron system (10), a cyclotron auxiliary system (20) and a cyclotron control system (30). The main cyclotron system (10) comprises an ion source (11), a central region (12), a superconducting magnet system (13), a radio frequency system (14) and a lead-out region (15). The ion source (11) is used for generating a proton beam; the central region (12) is used for leading out the proton beam of the ion source (11) and performing beam focusing inside the central region (12); the radio frequency system (14) leads out and accelerates the beam of the central region (12); a static magnetic field generated by the superconducting magnet system (13) can constrain the proton beam and accelerate same to target energy; the lead-out region (15) can lead out the proton beam.

The invention provides a pencil beam dose calculation method. The pencil beam dose calculation method comprises the following steps: acquiring human body image data; determining a plurality of particle types for treatment; calculating initial pencil beam dose distribution corresponding to each particle type; based on the particle types, target action layers, distributed in the human body image data, of all the doses are determined, and the positions of the target action layers corresponding to different particle types are different; based on the target action layer corresponding to each particle type, adjusting each initial dose distribution, and obtaining particle pencil beam dose distribution corresponding to each particle type; superposing the particle pencil beam dose distribution corresponding to each particle type to obtain target pencil beam dose distribution; wherein the dose proportion of the particle pencil beam dose distribution corresponding to the same particle type in the target action layer is greater than the dose proportion of the particle pencil beam dose of the particle type in other parts in the human body image data.

Disclosed are a neutron dose measurement apparatus and a neutron capturing treatment device. The neutron dose measurement apparatus includes a measurement unit for receiving neutrons and outputting signals, a signal processing unit for processing the signals output from the measurement unit, a counter for counting the signals output from the signal processing unit to obtain a count rate, and a count rate correction unit for correcting the count rate.