COSMOCal project
saturday september 28 2024
summary of operations :
friday september 27 2024
thursday september 26 2024
* with the source off, the hwp placed on the optical path but not spinning, we pointed the sky (close to the north pole) and then a source, on it we performed focus scans and pointing to check the corrections * we moved to the mm source by running track command on pako, using the coordinates known from holography * on the acquisition software, we looked for resonances and tuned them (with hwp still off), which was quite easy * we started spinning the hwp at nominal 3Hz frequency * we switched on the mm source along with the chopper, modulating at 1Hz * at first, we saw no signal, but then we realised that the source's polarizer was set to 0º, hence minimising the signal, so we turned it to ~45º the signal appeared, with the correct hwp + chopper modulations * at this point, we started procedure to maximise the signal, by tilting the mm source in Az and El : here came some problems --> lost resonances, irregular signal (appearing and disappearing) and we could not go back to initial situation * so we closed the vertex to see if the problem was in kids or in real signal, and we saw a constant signal of ~2kHz * we opened the vertex again, tuned the resonances and the situation was quite stable again, so we took 3 ON-OFF scans