The anode sensitivity of PMT with different photocathode surfaces varies with temperature not exactly the same, and the sensitivity variation coefficient is different for different wavelength. Refer to Fig. 1:

Fig. 1 Photocathode type and corresponding temperature coefficient of photomultiplier tube

Magnetic shielding can be added. In addition, it is generally required that the PMT is 10cm or more away from the object generating the magnetic field and 3mm or more from the ground housing to avoid dark noise increase caused by the electric field.

1 .Avoiding to expose the cathode surface; 

2. Do not knock; 

3. Preheat for 30 minutes before practical operation; 

4. Pay attention to keep away from light; 

5. Keep pins clean and free of dirt.

The voltage divider resistance ratio recommended in the PMT product sample booklet is a general data. Since the output linearity is affected by the voltage divider current and space charge, the user needs to optimize the voltage divider circuit in order to increase the upper limit of linearity.

Based on experience, aluminum materials are often used as darkroom materials, and the inside and outside are coated with black light absorbing materials to prevent reflection and scattering of light. Rubber ring can be added at the joint of components to avoid light leakage. In terms of thickness, a few layers of aluminum foil coated with black light absorbing material are enough to achieve light-shielding effect.

The light output is defined as the ratio of the total number of photons emitted by the scintillator to the incident radiation energy absorbed by the scintillator.

It can be seen from the definition that the measurement of light output involves accurate measurement of photon number emitted by scintillator. Considering the factors such as light collection efficiency and sensitivity of measuring instrument, the measurement of light output is too complicated and the measurement accuracy is not high. In practical application, relative light output is more used. The relative light output is defined as the relative value given by comparing the light output value of the measured scintillator with the standard scintillator sample. For example, taking the same size NaI (Tl) scintillator as the standard, measure the relative ratio of the full-energy peak site of the energy spectrum of the scintillator tested excited by the radioactive source of ¹³⁷Cs at 662keV γ-ray under the same measurement conditions.

The energy resolution refers to the minimum energy interval that a scintillation detector can measure for two incident particles of different energies.

The single-energy particle with energy E is incident in the scintillator and absorbed completely, and transforms to an excited light of the scintillator, transmits, and then is detected by a photodetector and processed by the circuit, so that the output pulse is a statistical distribution. The ratio of the full width at half maximum(FWHM) to the peak position of the distribution spectrum is defined as the energy resolution of the scintillation detector. The intrinsic energy resolution of the scintillator can be obtained by subtracting the contribution of the photodetector. In high energy physics experiment, the standard deviation σ after Gaussian fitting of pulse distribution spectrum is used as energy resolution, but its physical meaning is different.

The composite scintillator is to couple and package two or more different kinds of scintillators into a whole, so as to test different kinds of radiation and different energy.

The embedded source scintillator is to embed radioactive source into the effective volume of scintillator. It is mainly used to calibrate the energy scale of detector system and stabilize the peak value. The type of embedded source is mainly determined according to the actual use demand of the customer. Generally, it is americium source or cesium source.

The main function of the scintillator reflecting layer is to reflect, and improve the collection the scintillation light to the optical window of the scintillator. The main reflecting layer materials include magnesium oxide, titanium dioxide, barium sulfate, Teflon film, ESR film, etc. For the specific type and thickness of the reflecting layer, our company can provide the solutions according to the purpose and requirements of customers.

Change the internal high voltage, thereby change the gain of the photomultiplier tube and thus change the sensitivity. Light detecting module generally provides the control voltage(Vc) input and reference voltage(Vr) output pins, and can directly ultilize an external adjustable power supply as the Vc, or adjust the Vc by using the Vr and potentiometer, so as to change the internal high voltage.

When using control voltage input to control the gain, the reference voltage cable should be left floating and avoid connecting with other devices.

After exposing to light, the dark count will be high, and maybe return to normal after being placed or used for a period of time. The recovery time or whether it can recover to normal level is mainly related to light intensity and exposure time. If you cannot judge, please contact BHP.

It is normal for occasional jump points to occur during a few hours monitoring. The reason may be the random emission of thermoelectron on the cathode surface, but you should eliminate the electromagnetic interference in advance.

It is the minimum interval between adjacent pulses that can be distinguished by the detector, as shown in the figure below.

At least 20Ms^-1 linearity can be achieved when using with either the CH297 or CH368 counting unit (with linearity correction procedure). The corrected counting rate deviation data can be found in the datasheet of the photon counting detector module.

CS233, CS234 and CS235 lyophilized powder shall be stored at or below -20°C, and the resuscitation diluent and osmoregulation buffer shall be stored at normal temperature.

During the test, please standardize the operation, first configure the standard sample, then configure the sample to be tested, and use the disposable pipette tip for each configuration, that is: Replace the pipette tip with each configuration sample.

Recommendations: When standard sample and tested sample are placed on test tube rack, there shall be at least 1 space between standard sample and tested sample.

BHP9514 is an industrial resistive touchscreen with good stability and requires a touch pen to operate. The BHP9606 series product is android system, which adopts capacitive touch screen, and its sensitivity is higher than resistive touchscreen.

Other BHL models include color screens (android).

For XP, Win7, and Win10 systems, drivers that match different systems are provided, and the solution is to install corresponding drives for different systems.