A subset of the EPICS variables which read Hall A cryotarget information are displayed in the run-end halog entries, and are part of the epics events which are appended to the data stream about every 8 seconds. Below you will find a list of the hardware names and the connected sensor. The figure will give you the location of the temperature sensors in the loop and the pressure transducers in the gaspanel.
haBDSPOS | lifter position | |
haL1_Fan_frequency_R | loop 1 fan / Hz | |
haL3_Fan_frequency_R | loop 3 fan / Hz | |
haSC200_6_Sensor_1_R | PT255 / psi | |
haSC200_6_Sensor_2_R | PT267 / psi | |
haSC200_6_Sensor_3_R | PT265 / psi | |
haSC200_6_Sensor_4_R | PT259 / psi | |
haHe_Omega_DPG_Sensor_R | DPT269 / psi | not calibrated |
haITC502_1_Sensor_1_R | CT97 / K | |
haITC502_1_Sensor_2_R | CT96 / K | |
haITC502_1_Sensor_3_R | CT93 / K | |
haITC502_4_Sensor_1_R | CT94 / K | |
haITC502_4_Sensor_2_R | CT105 / K | |
haITC502_4_Sensor_3_R | CT116 / K | |
haITC502_5_Sensor_1_R | CT171 / K | |
haITC502_5_Sensor_2_R | CT170 / K | |
haITC502_5_Sensor_3_R | lead target / K | |
haITC502_6_Sensor_1_R | CT168 / K | |
haITC502_6_Sensor_2_R | CT169 / K | |
haITC502_6_Sensor_3_R | not connected |
The snapshot was taken when the target was warm.
In December, the pressure transducers were not shielded. After a few days of high beam, they started to drift, and their readings are essentially not usable. Before the experiment started, the target was filled up to 112.1 psi. The first logged reading (in e89044_1293.dat.0) was 109.5 psi. I don't know if this was a miscalibration or already radiation damage. It should be ok to assume that the target pressure was 112 psi trough December.
During the January shutdown, the transducers were shielded and calibrated, and additionally PT267 was moved behind the green wall. Focussing on PT267 only, it seems the transducer was reading fine, except for an slowly increasing offset versus the mechanical reading, which is believed to be accurate. The offset was +2.3 psi on February 25, +4.0 psi March 16, and +6.5 psi during E93049 (about end of April). This offset has to be added to the PT267 readings for February and March.
After commissioning, the temperature profile of the target was as follows:
Sensors CT97 and CT96 before the beam and CT93 after the beam were working all through E89044 and should be used to monitor the target temperature. It should be emphasized that CT93 gives only the indication that the gas temperature in beam is higher than the nominal one, but does not read this temperature.
Michael Kuss, July 24, 2000