WE WRITE AND POST THIS ENTRY A SECOND TIME SINCE IT WAS ERASED FROM THE LOGBOOK AFTER OUR FIRST ATTEMPT.

This morning we performed another round of alignment checks after the intervention in SDB1. 

Air flux is off, BS-SR valve open to let the NI single bounce beam reach the SDB1 bench, nitrogen blowing on the cryotrap window.

The suspension control of SDB1 were restored by Paolo yesterday night. SDB1 angular control are closed.

Noticing that the height of SBD2 has drifted away during the night, we remove a few temporary weights to adjut the bench height close to 500 um. Then we close SDB2 angular and position loops.

We then check the position of the beam on B1p camera. it is too high. Thefefore we change the SDB1 angular setpoints to recenter it : in TX setpoint changed from 60 to 15 um, in TY setpoints changed from 20 to 27 um. After this adjustment we checked the position of the B1s beam on the silicon beam dump on SBD2 (using an IR card) and it was found well inside the beam dump.

We open the OMC shutter and check that the B1s beam is well centered in its camera (Fig.1). Initially we read a power of about 40 mW on B1s (Fig.2). Then we checked that the B1s beam is still passing through the iris placed at the input of the EDB bench.

We performed an OMC scan and found the following powers per mode:

• TEM00 mode: containing a power of 1uW (see Figs. 3 and 4)
• 1st HOM: containing a power of 2uW (see Fig. 5 and 6)
• 2nd HOM: containing a power of 1.8uW (see Fig. 7 and 8)
• 3rd HOM: containing a power of 2uW (see Fig. 8 and 9)
• 4th HOM: containing a power of 2uW (see Fig. 10 and 11)
• 5th HOM: containing a power of 2uW (see Fig. 12 and 13 )

This makes a total of 10.8uW. Assuming a calibration factor of 4800 on B1_PD3, we get a total power of 52mW, compared to the B1s power of about 70mW.

We check that the B1p, B1s and B5 galvo loops centering is working well (Fig.14). In order to be able to close the B5_QD1 galvo loop we had to perform a little adjustment (order of 1500 counts) with the picomotors B5_M2. REMEMBER TO UPDATE THE NAMES OF THE PICOMOTORS WHICH ARE NOW VERY CONFUSING (B5_M1 for B5_QD2 now on the B1s beam, versus B5_M2 for B5_QD1).

This concluded our alignment check.

We close the OMC shutter, open the SDB2 local controls. Remove SDB2 temporary weights, remove EDB irises.

We close the SDB2 vacuum chamber and starts the pumping around 10h30 utc.

We ask the VAC team to close the BS-SR valve as we do not need the laser hazard in DET tower any more. The air flux in the tower is switched back on. We close the nitrogen bottle.