APDCAM User’s Guide
Page 14/32
APD#
Channel
APD#
Channel
APD#
Channel
APD#
Channel
A1 18 A2 19 A3 15 A4 14
B1 20 B2 17 B3 13 B4 12
C1 21 C2 22 C3 16 C4 11
D1 23 D2 24 D3 10 D4 9
E1 25 E2 26 E3 8 E4 7
F1 27 F2 32 F3 6 F4 5
G1 28 G2 29 G3 1 G4 4
H1 30 H2 31 H3 3 H4 2
Channel
APD#
Channel
APD#
Channel
APD#
Channel
APD#
1 G3
9 D4
17
B2
25
E1
2 H4 10 D3 18 A1 26 E2
3 H3 11 C4 19 A2 27 F1
4 G4 12 B4 20 B1 28 G1
5 F4 13 B3 21 C1 29 G2
6 F3 14 A4 22 C2 30 H1
7 E4 15 A3 23 D1 31 H2
8 E3 16 C3 24 D2 32 F2
Table 4. Allocation of data acquisition channels for the detector pixels.
The detector bias voltage determines the internal gain of the pixels. The gain as a
function of the applied voltage is shown together with the Quantum efficiency (QE) in
Figure 6
. Besides the gain the bias voltage also changes the detector capacitance, it de-
creases with increasing voltage. As all pixels are operated from a common bias voltage at
low voltage setting the crosstalk increases between channels which results in an increase
of the noise and its coherency between channels. Below about 150 V the 32 channel am-
plifier system oscillates between minimum and maximum output, therefore no measure-
ment can be done. The exact limit and the noise as a function of bias voltage depends on
the amplifier bandwidth but above 200 V bias voltage the detector is stable. The noise
level decreases slightly until about 300 V.
Figure 6. Detector typical Quantum Efficiency (QE) and Gain.
(Source: Hamamatsu S8550 datasheet.)