Patent Number: 
Section: claims

1. An apparatus comprising:a radiation absorption layer comprising an electrode;a counter;a controller configured to cause a number registered by the counter to change, in response to an absolute value of an electrical signal on the electrode equaling or exceeding an absolute value of a second threshold during a time delay that is started from a time at which the absolute value of the electrical signal equals or exceeds an absolute value of a first threshold. 2. The apparatus of claim 1, further comprising a capacitor module electrically connected to the electrode, wherein the capacitor module is configured to collect charge carriers from the electrode. 3. The apparatus of claim 1, wherein the absolute value of the second threshold is greater than the absolute value of the first threshold. 4. The apparatus of claim 1, further comprising a meter, wherein the controller is configured to cause the meter to measure the electrical signal upon expiration of the time delay. 5. The apparatus of claim 4, wherein the controller is configured to determine an energy of the radiation particles based on a value of the electrical signal measured upon expiration of the time delay. 6. The apparatus of claim 1, wherein the controller is configured to connect the electrode to an electrical ground. 7. The apparatus of claim 1, wherein a rate of change of the electrical signal is substantially zero at expiration of the time delay. 8. The apparatus of claim 1, wherein a rate of change of the electrical signal is substantially non-zero at expiration of the time delay. 9. The apparatus of claim 1, wherein the radiation absorption layer comprises a diode. 10. The apparatus of claim 1, wherein the radiation absorption layer comprises silicon, germanium, GaAs, CdTe, CdZnTe, or a combination thereof. 11. The apparatus of claim 1, wherein the apparatus does not comprise a scintillator. 12. The apparatus of claim 1, wherein the apparatus comprises an array of pixels. 13. The apparatus of claim 1, wherein the radiation particles are photons. 14. The apparatus of claim 13, wherein the photons are X-ray photons. 15. The apparatus of claim 1, wherein the electrical signal is a voltage. 16. A system comprising the apparatus of claim 1 and a radiation source. 17. A system comprising the apparatus of claim 1 and an electron source.