Radiation detector
There is provided a radiation detector that appropriately corrects an offset within a minute read cell without increasing area while achieving high-speed measurement at a high counting rate. A radiation detector 100 having a plurality of single-photon-counting imaging cells includes, for each imaging cell, a photodiode 3 which is applied with a reverse bias voltage and generates a current signal in response to incidence of radiation, a previous-stage DA converter d 1 configured to correct an input signal based on the current signal generated by the photodiode 3 , an amplifier k 2 configured to amplify the signal corrected by the previous-stage DA converter d 1 , a subsequent-stage DA converter d 2 configured to correct a charge signal amplified by the amplifier k 2 , a wave height discriminator 9 configured to discriminate output signals based on the signal corrected by the subsequent-stage DA converter d 2 , and a counter 10 configured to count the discriminated signals.
1. A radiation detector having a plurality of single-photon-counting imaging cells, comprising, for each imaging cell:
a photodiode which is applied with a reverse bias voltage and generates a current signal in response to incidence of radiation;
a previous-stage DA converter configured to correct an input signal based on the current signal generated by the photodiode;
an amplifier configured to amplify the signal corrected by the previous-stage DA converter;
a subsequent-stage DA converter configured to correct a charge signal amplified by the amplifier;
a wave height discriminator configured to discriminate output signals based on the signal corrected by the subsequent-stage DA converter; and
a counter configured to count the discriminated signals.
2. The radiation detector according to claim 1 , wherein
for each imaging cell, the corrected value by the previous-stage DA converter and the corrected value by the subsequent-stage DA converter are determined for the amplification factor of the amplifier so that the signal corrected by the subsequent-stage DA converter corresponds to the correction adjusted in advance between the imaging cells.
3. The radiation detector according to claim 1 , wherein
the wave height discriminator allows only a signal of radiation having energy in a predetermined range to pass.
4. The radiation detector according to claim 1 , further comprising a charge amplifier circuit provided in a stage prior to the previous-stage DA converter, wherein
the amplifier is a waveform shaping amplifier.
5. The radiation detector according to claim 1 , wherein
the amplifier includes a current amplifier circuit, and
each of the DA converters is of current output type.
6. A radiation detector having a plurality of single-photon-counting imaging cells, comprising, for each imaging cell:
a photodiode which is applied with a reverse bias voltage and generates a current signal in response to incidence of radiation;
an (n−1)-th DA converter configured to correct an input signal based on the current signal generated by the photodiode;
an n-th amplifier configured to amplify the signal corrected by the (n−1)-th DA converter;
an n-th DA converter configured to correct a charge signal amplified by the n-th amplifier;
a wave height discriminator configured to discriminate output signals based on the signal corrected by the n-th DA converter; and
a counter configured to count the discriminated signals, wherein
the (n−1)-th DA converter, the n-th amplifier, and the n-th DA converter are connected in series in the number from two to an integer N of two or more consecutively as to the integer n.
7. The radiation detector according to claim 6 , wherein
for each imaging cell, the corrected value by the (n−1)-th DA converter and the corrected value by the n-th DA converter are determined for the amplification factor of the n-th amplifier so that the signal corrected by the N-th DA converter corresponds to the correction adjusted in advance between the imaging cells.