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AdV-DET (Commissioning)
mwas, masserot - 11:17 Wednesday 19 September 2018 (42728) Print this report
Fast shutter trigger
Updated the Fast shutter triggers, there are many different ways to trigger the fast shutter:
* B1_PD1 > 14mW
* B1_PD2 > 14mW
* B1p_PD1 > 10mW
* B1p_PD2 > 10.5mW (previously was 14mW, but the PD shutter closes at 13mA, so this was never triggering in July/August, for fast transients 13mA corresponds to 11.5mW)
* B1s2_PD1 > 40mW
* LSC_ENABLE going down to zero - at ~15:38:20 on Sep 18, tested that it triggers correctly the fast shutter, and that the fast shutter reopens after 10s even if LSC_ENABLE is still at zero
manual close
* INJ_IMC_LOCK going down to zero - it is able to for example very safely catch the IMC unlocks caused by the SSFS boost engaged at LOW NOISE 1, hopefully also will work for IMC fast unlocks
* manual switch

Figure 1 shows the INJ_IMC_LOCK is dropping 50ms before an unlock
Figure 2 shows that with INJ_IMC_LOCK added to the fast shutter trigger logic the unlock flash on B1p PD2 is not visible at all

There is work in progress to replace the trigger on PDs from the power in mW to current in mA, might be tested this afternoon. In that way the trigger quantity would be exactly the same for the PD shutter and the fast shutter, which would avoid the issue that fast transients break the linear relation between current and calibrated power. This will be more robust and allow a looser threshold on B1p_PD2.
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