APD detector

Nuclear scattering is counted by two avalanche photo diode (APD) detectors. The detector for NIS (Fig. 9.1) is located close to the sample. It counts the quanta scattered in a large solid angle. The detector for NFS is located far away from the sample. It counts the quanta scattered by the nuclei in the forward direction. These two detectors follow two qualitatively different processes of nuclear scattering ... 

Recently, a 128 x 128 CMOS APD detector has been produced at the ETH Lausanne (EPFL). This development will provide a 10 pixel area for simultaneous kinetic and d mamic analysis with a time resolution of ns and... 

Single photon avalanche photodiodes (SPADs) achieve the highest radiant sensitivity of all detectors in the NIR. Currently available APD detectors have ex-... 

A troublesome effect in photon correlation experiments is light emission from single photon APD detectors. When an avalanche is triggered in the APD, a small amount of light is emitted. The effect and its implications for photon correlation experiments and quantum key distribution are described in detail in [515] and [299]. If the detectors are not carefully optically decoupled, false coincidence peaks appear. An example is shown in Fig. 5.105. 

APDs suitable for single photon detection must be free of premature breakdown at the edge of the junction or at local lattice defects. So far, only selected silicon APDs can be operated in the passive or active quenching mode, and only a few single photon APD detectors are commercially available [245, 354, 408]. 

Schematic for measurement of the nuclear resonance excitation accompanied by phonon excitation. The avalanche photodiode (APD) detector placed below the sample detects inelastic scattering, and another APD detector in the forward direction detects forward scattering for the energy reference...

To further improve the performance of the APD detectors for nuclear resonant scattering applications, the high-degree suppression of the nonresonant radiation is essential. This is achieved by using high-resolution monochromators... 

All the above applications indicate that SRPAC is a promising new technique to study hyperfine interactions of Mossbauer isotopes, especially for the isotopes with small Lamb-Mossbauer factors, because of the unique feature of SRPAC— the intensity is independent of the Lamb-Mossbauer factors. However, future developments of this technique has to be done in the direction of increasing the efficiency and the detection area of the APD detector and optimizing the monochromators, especially for the high transition energy Mossbauer isotopes (such as Ni with 67.4 keV nuclear resonance energy) so that SRPAC can be regularly applied to protein studies. 

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