Today Caroline C. and I took PS4 down to EX to follow the directions on DCC Doc T1500062 for the End station measurement.
This was the First ES measurement since the EndX station was Vented, Thankfully I had recently done an EX measurement last month!
Note for PEM crew: While setting up for our measurement, the leg (#2) for a tripod holding an Accerlerometer/microphone slipped and fell at ~9:22 am -ish Local time. Tagging PEM.
Checking the Beam spots before we started, I was happy to see that we still have both beams, And the beams are well aligned!
While I was adjusting the beam block in the TX module we noticed that when I was checking for light behind the beam dump the WS sphere responded to the beam card's placement behind the beam block. I think what was going on is similar to what we saw in the lab where the diffuse light coming out of the sphere's apature is interacting with objects upstream of the apature and reflecting back. I then decided to move the beam blocks to before the steering mirrors.
Oh I was checking for the I limit LED to turn on, It never did, which is a good sign. I beleive this is the current limit LED and happens when there are power fluctuations.
After the measurement I check the Beam spots again. Looks good.
Command that were ran to make analysis happen:
@cdsws25: python3 generate_measurement_data.py --WS PS4 --date 2026-08-24
Reading in config file from python file in scripts
../../../Common/O4PSparams.yaml
PS4 rho, kappa, u_rel on 2026-08-24 corrected to ES temperature 300.1 K :
-4.698238515939288 -0.0002694340454223 0.00075040881877916
Copying the scripts into tD directory...
Connected to h1daqnds1
martel run
reading data at start_time: 1474131650
reading data at start_time: 1474132080
reading data at start_time: 1474132460
reading data at start_time: 1474133220
reading data at start_time: 1474133630
reading data at start_time: 1474134000
reading data at start_time: 1474134200
reading data at start_time: 1474134850
reading data at start_time: 1474135230
Ratios: -0.4613044966821107 -0.4660884801303913
writing nds2 data to files
finishing writing
Background Values:
bg1 = 9.463727; Background of TX when WS is at TX
bg2 = 5.116111; Background of WS when WS is at TX
bg3 = 9.483908; Background of TX when WS is at RX
bg4 = 5.220218; Background of WS when WS is at RX
bg5 = 9.517908; Background of TX
bg6 = 0.309874; Background of RX
The uncertainty reported below are Relative Standard Deviation in percent
Intermediate Ratios
RatioWS_TX_it = -0.461304;
RatioWS_TX_ot = -0.466088;
RatioWS_TX_ir = -0.455459;
RatioWS_TX_or = -0.460916;
RatioWS_TX_it_unc = 0.073428;
RatioWS_TX_ot_unc = 0.073806;
RatioWS_TX_ir_unc = 0.072766;
RatioWS_TX_or_unc = 0.078002;
Optical Efficiency
OE_Inner_beam = 0.987351;
OE_Outer_beam = 0.988996;
Weighted_Optical_Efficiency = 0.988174;
OE_Inner_beam_unc = 0.047979;
OE_Outer_beam_unc = 0.050724;
Weighted_Optical_Efficiency_unc = 0.069821;
Martel Voltage fit:
Gradient = 1636.905374;
Intercept = 0.141593;
Power Imbalance = 0.989736;
Endstation Power sensors to WS ratios::
Ratio_WS_TX = -1.078292;
Ratio_WS_RX = -1.391839;
Ratio_WS_TX_unc = 0.044772;
Ratio_WS_RX_unc = 0.038846;
=============================================================
============= Values for Force Coefficients =================
=============================================================
Key Pcal Values :
GS = -5.135100; Gold Standard Value in (V/W)
WS = -4.698239; Working Standard Value
costheta = 0.988362; Angle of incidence
c = 299792458.000000; Speed of Light
End Station Values :
TXWS = -1.078292; Tx to WS Rel responsivity (V/V)
sigma_TXWS = 0.000483; Uncertainity of Tx to WS Rel responsivity (V/V)
RXWS = -1.391839; Rx to WS Rel responsivity (V/V)
sigma_RXWS = 0.000541; Uncertainity of Rx to WS Rel responsivity (V/V)
e = 0.988174; Optical Efficiency (compare from from last month!------->: 0.988725; Optical Efficiency)
sigma_e = 0.000690; Uncertainity in Optical Efficiency (compare from from last month!------->: 0.000661; Uncertainity in Optical Efficiency)
Martel Voltage fit :
Martel_gradient = 1636.905374; Martel to output channel (C/V)
Martel_intercept = 0.141593; Intercept of fit of Martel to output (C/V)
Power Loss Apportion :
beta = 0.998895; Ratio between input and output (Beta)
E_T = 0.993520; TX Optical efficiency
sigma_E_T = 0.000347; Uncertainity in TX Optical efficiency
E_R = 0.994619; RX Optical Efficiency (compare from from last month!------->: 0.994896; RX Optical Efficiency)
sigma_E_R = 0.000347; Uncertainity in RX Optical efficiency (compare from from last month!------->: 0.000332; Uncertainity in RX Optical efficiency)
Force Coefficients :
FC_TxPD = 7.899630e-13; TxPD Force Coefficient (compare from from last month!------->: 7.900632e-13; TxPD Force Coefficient)
FC_RxPD = 6.193277e-13; RxPD Force Coefficient (compare from from last month!------->: 6.191631e-13; RxPD Force Coefficient)
sigma_FC_TxPD = 3.755608e-24; TxPD Force Coefficient (compare from from last month!------->: 3.624112e-24; TxPD Force Coefficient)
sigma_FC_RxPD = 2.797039e-24; RxPD Force Coefficient (compare from from last month!------->: 2.753947e-24; RxPD Force Coefficient)
data written to ../../measurements/LHO_EndX/tD20260922/ and can be found at the gitlab pcal repo
I added a little context for those that may be wondering if there was an decrease in Optical efficiancy, uncertainty, Force, or Displacement due to the EX venting. The numbers in bold are from last month's alog 91681 to show that things have not seen much change at all. We did not have a repeat of LLO's EX vent experience! YAY!
For see how these measurements compare with all of the measurements for the past few years click here!
