====== Capacitance Measurements ======
The goal is to measure the capacitance of the detectors which are in use in the high energy beam lines as a fiction of frequency. This information can be used in to simulate detector response and for diagnostics of the detector health. For instance defect cables can be discovered by controlling the detector capacitance.

===== Measuring equipment and measurement procedure =====
  * Keysight U1733C, Handheld LCR Meter. Used to determine C at 100 Hz, 120 Hz, 1 kHz, 10 kHz, 100 kHz
  * Keysight N9917A network-analyser.  S11 measured at frequency larger than 30 kHz. The maximum measurement frequency is set automatically by selecting maximum cable length of 1 m in the TDR measurements, or to 10 <nowiki>MHz</nowiki> when S11 is recorded.

==== Keysight U1733C ====
  * Using the ZLCR button select C with serial resistance.
  * Select the measurement frequency with the Freq. button
  * Lave the rage to Auto
  * After connecting the measurement cable select Δ Null. Hence, a relative measurement is done

==== Keysight N9917A ====
  * In the cable menu: More -> TDR ( Ohm )
  * Setup: Start = 0 m, Stop = 1m
  * Out power: High
  * VF = 0.7

For S11 measurement, select NA and set Start F = 30 kHz, Stop F = 10 <nowiki>MHz</nowiki>

For all measurements perform quick calibration with SMA open and 50 Ohm load from the Nano-VNA set

===== Detector C for low frequencies =====
^ Detector ^  F [kHz] ^  C [pF] ^  Θ [deg] ^
| Ref.Cal. L=65cm |  0.100 |  66.1 |  -89.0 |
|          |  0.120 |  67.2 |  -89.7 |
|          |      1 |  67.1 |  -89.8 |
|          |     10 |  67.0 |  -80.0 |
|          |    100 |  66.9 |  -89.1 |
| FAIR-SEM |  0.100 |  124.8 |  -89.8 |
|          |  0.120 |  124.8 |  -89.8 |
|          |      1 |  124.5 |  -89.8 |
|          |     10 |  124.1 |  -80.0 |
|          |    100 |  123.8 |  -89.2 |
| FAIR-IC  |  0.100 |    228 |        |
|          |  0.120 |    227 |        |
|          |      1 |    226 |        |
|          |     10 |  225.8 |        |
|          |    100 |  223.3 |        |
| BLM-IC   |  0.100 |  428.5 |        |
|          |  0.120 |  428.5 |        |
|          |      1 |  428.7 |        |
|          |     10 |  427.9 |        |
|          |    100 |  426.8 |        |
| BLM-PC   |      1 |      8 |        |

==== S11 measurements ====
{{ :hi:detectorcapasitance:sem_smith_18.sep.2024.07.46.s1p.gz |S11 FAIR-SEM}}