SU1659936A1 - Device for searching nuclear photoemulsion - Google Patents

Abstract

The invention relates to nuclear physics, namely to experimental elementary particle physics, and can be used in the study of short-lived elementary particles on neutrino beams from an accelerator. The purpose of the invention is to increase the reliability of detecting particles of a given orientation by increasing the signal-to-noise ratio. Two differentiating units 5, two inverters 6 were inserted into the device containing the system 1 for forming mesoscopic images of direct traces of particles of a given orientation, unit 2 for moving and controlling the position of a nuclear photo emulsion, two light guides 3, two photodetectors 4 and unit 9 for recording and processing signals. four discriminators 7 and four timers 8. In block 9 for recording and processing signals, four photo pulses are received from each direct trace of particles of a given orientation, the delay between which determines the Z-coordinate of the direct trace astitsy, and the average time of occurrence of four photopulses - x-coordinate as direct particle track. 1 silt (L with about a

Description

The invention relates to nuclear physics, namely, experimental elementary particle physics, and can be used in the study of short-lived elementary particles on accelerator neutrino beams.

The aim of the invention is to increase the reliability of detecting particles of a given orientation by increasing the signal-to-noise ratio.

The drawing shows the functional diagram of the device for viewing nuclear emulsion.

The device contains a system 1 of forming mesoscopic images of direct traces of particles of a given orientation, a unit 2 for moving and controlling the position of a nuclear photo emulsion, two light guides 3, two photodetectors 4, two differentiating units 5, two inverters 6, four discriminators 7, four timers 8 and block 9 recording and signal processing.

The light guides 3 are docked by the input ends to the mesoptical mirror of the system 1 for forming mesoptical images of direct tracks of particles of a given orientation in the place where the mesoptical images are located, and by the output ends of the first and second photodetectors 4. The outputs of the first and second photodetectors 4 are connected to the inputs respectively, the first and second differentiating units 5. The first differentiating unit 5 is connected by the first output through the first discriminator 7 to the information input of the first timer 8 and t By the output through the serially connected first inverter and the second discriminator 7 to the information input of the second timer 8. The second differentiating unit 5 is connected by the first output through the serially connected second inverter 6 and the third discriminator 7 to the information input of the third timer 8 and the second output through the fourth discriminator 7 to the information input the input of the fourth timer 8. The outputs of all timers 8 are connected to the corresponding information inputs of the recording and processing unit 9 of the connected control yuschim input to the control inputs of all of the timers and 8 to the output unit 2 and controlling the movement position nuclearencoded emulsion.

A device for viewing nuclear emulsion works as follows. The system includes the formation of meso-optical images of direct traces of particles of a given orientation, the unit 2 of movement and control of the position of the nucleus.

emulsions, photodetectors 4, differentiating units 5, inverters 6 signals, discriminators 7, timers 8 and unit 9 for recording and processing signals. The nuclear emulsion is placed in the working position and the velocity of v is set in block 2.

The system 1 for forming mesoscopic images of direct traces of particles of a given orientation creates two mesoptical images that are located near the input ends of the optical fibers 3 and are parallel to the orientation of mesoscopic images of a direct trace of a particle.

5 preset orientation. Meso-optical images of the direct trace of the particle fall on the input ends of the optical fibers 3 at different times, and the difference between them is a measure of the z-coordinate of the observed trace of the particle. Photocurrent signals in photo receivers 4 arise when the motion of a nuclear emulsion is unceasing. Each of them has the form of a photocurrent pulse l (t), weakly rising above

5 background. The total signal from the photocurrent pulse l (t) and the background (t) from the outputs of photodetectors 4 undergo time differentiation from the corresponding differentiating units 5. Two outputs of each differentiating block 5 produce two components of the differentiated photocurrent signal: positive and negative.

Both components of the signals from the outputs

5 differentiating blocks 5 are subjected to amplitude discrimination in the discriminators 7 of each arm of the device, while the negative component of the signal first passes through the corresponding

0 Inverter 6, A total of four signals are generated: two in the left and two in the right arms of the device. The times of occurrence of the four signals are counted using four timers 8. Clock

5, time signals are generated at the output of the unit 2 for moving and controlling the position of the nuclear emulsion and are fed to the control input of all the timers 8.

The process of viewing a nuclear photo0 emulsion is carried out in a mode of almost uniform displacement of the nuclear photoemulsion relative to the center of the field of view of the device at a speed of v. If the step of counting unit 2 moves and controls

5 position of the nuclear emulsion is equal to Ah, then the clock frequency of the gating pulses is equal to Dx.

So, for mm / s and Dx 1 µm has MO kHz.

The inconvenience of the speed of moving the nuclear photo emulsion will not affect the accuracy of measuring the time of occurrence of signals by timers 8, since simultaneously with a decrease (increase) in the speed of movement v, the frequency of tracking of the pulse pulses at the output of the movement 2 and control of the position of the nuclear photo emulsion will correspondingly decrease (increase).

For each particle trace, in block 9 of recording and processing signals, the values of four counts of the time of occurrence of a positive impulse of the left meso-optical image rV, negative impulse

meso-optical image as well

the corresponding values of t $ - and tЈ- for the right mesoptical image. At the same time, the coordinate x of the registered trace of a particle is determined by the formula:

x V Tlf + Tl + A + TR i (1)

and the z coordinate - according to the formula

z V (rV + zk + zR) (2)

Differences

() one

() / (h)

carry information about the effective diameter of the light guides 3 and are constant values. They can be used as criteria for extracting a useful signal from the background. Namely, if the difference is 5 | or SR has a non-standard value, this indicates unambiguously that the observed four photocurrent pulses are caused by random fluctuations of the background illumination. To verify this conclusion, measurements are made at this point again.

If in the process of moving the nuclear emulsion relative to the center of the field of view of the device, the direct trace of particles falls into the field of view of the device, then the ends of the optical fibers 3 are illuminated by narrow strips of light and at the output of both photodetectors

4 photocurrent signals are generated. Pass through the corresponding differentiating blocks

5 and inverters 6, the converted signals arrive at the information inputs of the timers 8. The value of the time points of the four photocurrent pulses

The TC,,, 1%, and TP are entered in block 9 of the signal recording and processing. Upon completion of the viewing of the nuclear emulsion, the operator calls all the received information from the block 9 for recording and processing the signals and

discards all background combinations of the four recorded signals. On average, the number of useful events in the form of direct traces of particles of a given orientation of 5 is 8–10 in a given area of nuclear emulsion with an area of 1 cm.

The use of the invention improves the reliability of the detection of a particle of a given orientation by improving the signal-to-noise ratio achieved by the fact that differentiated images of the photocurrent signals containing information about the fluctuation component of the signal are observed and recorded in this device.

Claims (1)

Invention Formula A device for viewing a nuclear photo emulsion containing a unit for displacing and controlling the position of a nuclear photo emulsion, two light guides, two photodetectors, a two-channel recording and signal processing unit, and a formation system 5 meso-optical images of direct traces of particles of a given orientation, consisting of a source of coherent light beam, a Fourier transform lens and a meso-optical mirror, to which are connected 0 both light guides are input ends and output ends to the inputs of the first and second photodetectors, respectively, characterized in that, in order to increase the reliability of the detection of particles given 5 orientation by increasing the signal-to-noise ratio, two differentiating units, two inverters, four discriminators and four timers are entered into it, and the signal recording and processing unit is four-channel and controllable and connected to the output of the displacement and control unit nuclear emulsion and to the control inputs of all timers, the outputs of the first and second 5 photodetectors are connected to the inputs of the first and second differentiating units, the first differentiating unit is connected via the first discriminator to the information input of the first timer and the second output via the first inverter connected in series and the second discriminator to the information input of the second timer, the second differentiating unit is connected to the first 5 output via serially connected second inverter and third discriminator to the information input of the third timer and the second Exit through the fourth discriminator to the data input of the fourth timer, the outputs of all 716599368 the timers are connected respectively to the permutation inputs of the recording unit and the front, second, third, and fourth information signals.