I analyzed the data acquired on March 24th from HWS-INJ (59402).

First I checked the intensity of the beam and the position of the maximum to understand if what has been seen on DET (59347 and 59334) also happens on INJ.

The jump is indeed present (fig.1). Since this is happening on BOTH HWS, it is not something peculiar to the HWS setup, rather something that involves the ITF alignment. According to the investigations done today, this seems to be related to the ETMs mis-alignment when unlocking (59431). Since keeping the ETMs may have bad effects as well (59155), we need to look for a workaround.

Anyway, I resumed and updated an ancient (2009?) code that allows to choose an arbitrary set of frames as reference for the calculation of the WF, and used live frames #5, since the drop occurs at that time.

The new wavefronts are saved in /data/tcs/buffer/test/HWS-RC/INJ/20230324T0004/WaveNew/. Fig. 2 shows one of these new WFs. The measurement is noisy, since the intensity is really low. Anyway, the YAG appears in the bottom left corner, more or less in the same position where the CH was appearing on March 22nd (59385).

The CH flipper was opened by the automation around WF 118. So, I used the frame set #118 as reference and calculated the following WFs. Data are saved in the same folder, the filename ending with “_CH”. The result is shown in fig. 3.

YAG and CH appear close, but it is really difficult to quantify the relative alignment between the two, due to the current status of the HWS-INJ beam.