Radon Detector (English)

Radon detector is composed of three parts, which are the detection of α-ray, the pulse height analyzer, the data control.

Detection of α-ray

Silicon PIN photodiodes (S3590-09, HAMAMATSU) is used for the measurement of α-ray as a semi-conductor detector. The incident α-ray stops inside the PD due to the ionization energy loss. Then electric signal occurs which correspond to energy of α-ray, where about 10^6 electron-hole pairs are created.

PD.png

Pulse height analyzer

Electric signal from PD is so weak that an electric circuit to amplify and shape the signal is needed. In our pulse height analyzer, FET input audio operational amplifier (OPA134, input bias electric current is 5pA) is adopted for charge integrating pre-amplifier. By combining CR differentiating circuit and two steps of RC integrating circuit, which have 20μ[sec] time constants, the pulse height of the signal is amplified up to more than several volts. Besides, this part has comparator circuit for giving trigger signal to microprocessor, and sample and hold circuit to hold the pulse height of the signal.

Data control

board.png

Circuit boards

Circuit diagrams and boards layouts for latest version can be found in the below.


添付ファイル: fileboard.png [詳細] filePD.png [詳細]

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Last-modified: 2014-07-24 (木) 16:45:10 (1214d)