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project:scintillation_counter:start

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project:scintillation_counter:start [2016/11/28 02:33] – ruzaproject:scintillation_counter:start [2017/03/09 16:14] (current) – ruza
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 +====== Scintillation counter ======
 +
 +{{template>:project:infobox|
 +name=Scintillation counter|
 +image=radiation_measurement.png?200|
 +sw=-|
 +hw=BSD|
 +founder=[[user:pinky]]|
 +interested=[[user:pinky]]\\ [[user:ray]]|
 +status=terminated
 +}}
 +
 +~~META:
 +status = terminated
 +&relation firstimage = :project:radiation_measurement.png
 +~~
 +
 +Sensitive detector of radiation (mainly beta and gamma).
 +
 +{{ :project:sensitive_radiation_detector.jpg?200 | Brmlab's scintillation radiation detector. }}
 +
 +  * [[:project:scintillation_counter:Experiments]] 
 +
 +TODO
 +  * dedicated voltage source
 +  * dedicated electronics for singnal acquisition
 +     * amplifier
 +     * AD converter
 +     * evaluate software (counter, try spectroscopy etc.)
 +===== Schematics and specifications =====
 +
 +{{:project:photomultiplier.svg| Schematic - connecting photomultiplier tube to hi-voltage source and output.}}
 +
 +  * Photomultiplier: is made by Tesla, the type is unknown.
 +  * Scintillator: is a block of plastic material named SP32. It is made out of para-terphenyl with POPOP (1,4-bis-(5-phenyl-2-oxazolyl)-benzene) solved in stirene, elmuSSo is used as condenser.
 +
 +===== Building workflow =====
 +
 +=== Step 1 - polishing FAG ===
 +
 +{{:project:01-polished_fag.jpg?200 | Polished FAG - scintillation plastic}}
 +{{:project:02-fag-uv_and_laser_iradiation.jpg?200 | blue glow of FAG in UV radiation}}
 +
 +FAG, the block of plastic used as scintillator, it's surface contained some unevenness from cutting process.
 +
 +The goal of polishing is to make the surface flat and transparent. Abrasion was made by sanding and then polishing paste. All abrasion was made with water due to cooling. But some overheating was not avoided and minor fractures occured.
 +
 +Polished FAG glows nice in UV radiation, red LASER added for effect.
 +
 +=== Step 2 - wrap FAG in aluminium ===
 +
 +{{:project:03-fag_in_al.jpg?200 | FAG wrapped in aluminium}}
 +{{:project:04-fag_in_al_with_top_hole.jpg?200 | FAG wrapped in more aluminium}}
 +{{:project:05-ductaped_fag.jpg?200 | FAG wrapped in aluminium and black ducktape}}
 +{{:project:06-more_ducktaped_fag.jpg?200 | FAG wrapped in aluminium and light-proof black plastic}}
 +
 +Polished FAG was wrapped into aluminium foil (2 layers) and black plastic plastic (2 lyers) using black sellotape. On the top remains a hole for photomultiplier.
 +
 +=== Step 3 - framing ===
 +
 +{{:project:07-scintillator_in_holder.jpg?200 | Scintillation counter frame}}
 +{{:project:08-attaching_photomultiplier.jpg?200 | Scintillation counter frame}}
 +
 +Finished scintillator with shielding was put into prepared frame. Frame is made from threaded rod and plastic part printed on RepRap.
 +
 +=== Step 4 - attaching photomultiplier ===
 +
 +{{:project:09-bitumen_glued_photomultiplier.jpg?200 | Photomultiplier fitted into frame glued with bitumen.}}
 +{{:project:10-photomultiplier_cover.jpg?200 | Photomultiplier cover attached.}}
 +{{:project:11-wiring_for_photomultiplier.jpg?200 |Top cover of photomultiplier with plugs for feeding and pulse counting.}}
 +
 +Photomultiplier is attached to the scintillation plastic by some kind of very viscous silicone oil in order to keep good optical contact. Bitumen was put betwen the frame and photomultiplier, it keeps the photomultiplier in place and stops any light from outside. Last step was imbed covering tube for photomultiplier, this was made from metal drain pipe. Final step is attaching electronic interface and top cover. All wraped in black sellotape.
 +
 +=== Step 5 - testing ===
 +
 +{{:project:osciloscope_a.jpg?200 | osciloscope when only background radiation is present}}
 +{{:project:osciloscope_b.jpg?200 | osciloscope when small sample of pitchblend is 30cm away from detector, approx. 1800 Bq (Hz)}}
 +
 +Laboratory source of high voltage was attached and set to approx. 1400V. Osciloscope was attached for measurement. As source of radiation we used a small piece of pitchblend (few grams in weight). It was positioned 30cm from detector. The result is impressive. Further tests are in progress.