Digital Ion ChamberController
DIGITALIZATION ACHIEVESREMOTE MEASUREMENTNOISE-FREEDigital Ion Chamber

Ion chamber
Digitizer
Controller

Characteristics of Digital Ion Chamber
What Is Digital Ion Chamber?
An ion chamber is a typical analog detector for measuring radiation intensity from the ionization
current of gas. With its simple structure and high linearity and dynamic range, ion chambers havebeen used for a long time as radiation intensity monitors.
Analog type ion chambers are weak in noise and not suitable for remote measurement with useof a micro current amplifier, and requires a high-cost micro current measurement system. Analog
ion chambers are widely used as beam monitors in radiation light facilities. However, needs forremote operations, including range switching, have increased in recent years.

Mechanism of Digital Ion Chamber
The mechanism of the ion chamber is same as that of analog types, but the digital ion chamber ischaracterized by the detector itself with a digital frequency output in proportion to the current.
This output being converted to an optical pulse and led by the optical fiber, enables long- distance(30m in standard) remote measurements and is also strong in noise. Range switching is easily
achieved with the controller at hand. An optical pulse is outputted after being converted to a TTL
pulse, and can be directly inputted into your scaling circuit. Also, in the range of or above10-8A,
the micro current amplifier offers a measurement system with performance equivalent to or
exceeding that of high class amplifiers, achieving excellent cost performance. The power supplyfor the ion chamber is not required.

Structure of Digital Ion Chamber
Analog/Digital conversion circuit

Ion chamber

Composition of Digital Ion ChamberPre-amplifier

Optical fiber

BeamIon chamberCounter
TTL pulse

Computer

2ch controller

Composition of Digital Ion Chamber(1) Number of preamplifierconnections(2) Input signal- Max. of 2 sets

(7) Bias voltage forchamber- Optical frequency signal

Output voltage
outputVoltage setting
accuracy
Ripple noise(8) Indicator indication
accuracy(3) Output signal- Frequency signal output+5V, 0.5μsec(TTL level)
10-13 – 10-9(A): 1MHz/10-9(A)10-12 – 10-8(A): 1MHz/10-8(A)
10-11 –10-7(A): 1MHz/10-7(A)10-10 – 10-6(A): 1MHz/10-6(A)(4) Accuracy- ±2%FS or less (For eachrange of 10-610-710-8A)(5) Integral linearity- ±3%FS or less
(Range 10-9A)- ±0.1%FS or less

(6) Analog output- 0–10VFS- 0 – +3000V (Dial valuex3)- ±0.5%FS or less
- 30mVp-p or less
- ± 0.5% FS or 2 dig or less

Indicator switch/ output
frequency and bias
voltage(9) Over level indication - Lights up when the output
frequency is equal to orabove 1.03 MHz.
(10) Pre-amplifier gain
- 4 position switchingswitch(11) Connection with the - Signal (frequency) output
pre-amplifierSignal (frequency)
output: Optical connector
High voltage input: Coaxial connector
Low voltage and gain control: Multipoleconnector(12) Dimensions- NIM standard 2 widthmodule(13) Required power
supply- +24V:160mA, +12V:85mA,-24V:35mA,12V:35mA

The Digital Ion Chamber Installed In Photon Factory
Linearity of Digital Ion Chamber

The digital ion chambers (Specific to photonfactories) for incident beam and IO (left) and fortransmission beam and I (right) are installed,with the sample between them. The output of theion chamber is led to outside the hatch(laboratory) by the optical fiber, and the numberof pulse for a preset time is measured.

The graph showing linearity of the digital ionchamber, shows a high linearity between theincident beam intensity (x-axis) and thedigital ion chamber output (y-axis).

Measurement Example:

Digital ion chambers (Designed specific toSPring-8) for incident beam and IO (left) and fortransmission beam and I (right).

A sudden change (jump in the graph) in
incident beam intensity caused by gap
tuning of SPring-8 undulator is completely
standardized. Results of the remotemeasurement at a distance of 30 meters.

Features Conversion to optical frequency signal/ electric frequency signal (I/F signal)
 External output of I/F signal
 Output signal monitor (4-disit LED indicator)
 Output frequency and high voltage output
 Over level indication (LED lamp) Bias power supply for the chamber and power supply for the I/F circuit.
 Pre-amplifier gain switching[Standard System Composition](1)(2)(3)(4)

Pre-amplifier (S -2340A):
2 units
Controller (S -2341A):
1 unitConnection cable- Between the chamber and pre-amplifier for high voltage (Low noise)x2
For signal (Low noise)x2- Between the pre-amplifier and controller Composite cable (5 m)x2Operation manual (Test report)
The composite cable between the pre-amplifier and controller can be made up to a length of 540 m, in units of meters.
When cables with length other than standard length (5m) are needed, please specify the length
when ordering.
A single pre-amplifier can be purchased.

OHYO KOKEN KOGYO CO., LTD
Head office/Factory:
Osaka Business Office:Higashimatsuyama Factory:

1642-26,Oaza-Kumagawa, Fussa city, TOKYO
197-0003, JAPAN
4-4-63, Miyahara, Yodogawa-ku, OSAKA,
JAPAN
88-77,Oaza-Shingo,Higashimatsuyama city,
SAITAMA, JAPAN+81-425-52-4511 (main)+81-6-394-4168 (main)+81-493-23-9515 (main)