Report from BESSY 10/14/97

This is the first report from our calibration efforts at BESSY.

The equipment was waiting for us when we arrived on Sunday Oct. 12th, minus the ssd_5 detector. This did arrive on Monday Oct. 13th. The equipment survived the shipping process except for an RTD indicator in the electronics rack. The RTD indicator electronics fell out of its "box" during shipment. Since we must not use the RTD during measurements this is not an issue.

We had the computer system up and operational, and the ssd_x detector mounted to the beamline by 7:30 pm Sunday night. We saved the computer software modifications to the cci scripts until Monday morning.

When we arrived Monday morning, we found that a pin that holds a screw used to move the gate valve for the ssd had sheared off and we could not get the gate valve open. A call to the manufacturer told us that we were able to remove part of the gate valve to replace the pin without compromising the vacuum. This was completed about 3:30 pm Monday. We started collecting data approximately 4:00 pm yesterday.

We are using a Si monochromator instead of an InSb crystal that was used last time. The measurements for this crystal range from 1.7 keV to 5.9 keV. We are going in steps of 200 eV. The measurements with this crystal are expected to last until 4:00pm today (Tuesday Oct 14). At this time we will switch to the Beryl crystal to cover the range from 1.1 to 1.7 keV. We will concentrate some of these measurements around the Ge-L edge and the Al-K edge.

When we start using the Beryl crystal, we will only be able to open the beam shutters when the storage ring current gets below 400 mA due to the heat load on the crystals which could destroy them if not careful. The usual injection starts at 700 mA so we must wait for the beam to decay until we are able to get x-rays. This problem was thought to be solved previously by placing a thick beryllium filter in front of the monochromator, however they have since learned that this was not effective and there was still damage to the crystals.

The implications of this are we will start running 20 hours/day starting to night. The last injection occurs at 10:00 pm (The Dawn Special). This injection is allowed to run until the next morning at 7:00 am (i.e. until dawn!). Normally the ring is reinjected every 4 hours to keep the current high.

Given these "limitations", we have calculated we will still have time to finish the measurements we have planned.

Measurements 10/13/97

Listed as: RunID, CMDB ID, & Comments

• 500230, L-IXS-RF-2.14, Note: RF means Response Function 2.1 keV
• 500231, L-IXS-RF-2.14, Repeat with a different detuning factor of the monochromator
• 500232, L-IXS-RF-2.15, 2.3 keV
• 500233, L-IXS-RF-2.15, Repeat w/ new detuning factor
• 500234, L-IXS-RF-2.16, 2.5 keV
• 500235, L-IXS-RF-2.17, 2.7 keV
• 500236, L-IXS-RF-2.18, 2.9 keV Beam dumped after 300 seconds

Plan: 10/14/97

• Continue with the Si monochromator up to 5.9 keV.
• Repeat some of the measurements done yesterday for repeatability checks.
• Switch to the Beryl crystal approximately 4:00 pm
• Start running the Beryl crystal at 8:00 pm until 10:00 pm when the last injection of the day is done.
• Continue running starting at 12:00 am until the Beryl measurements are complete.
• Remove the SSD_X from the beamline and mount the SSD_5 to the beamline to get ready for testing tomorrow morning.

Results:

The Si monochromator spectrum is quite clean. The interpeak events are about 0.02% of the main peak. The second order contamination is very small. It appears that the 2xEnergy peak is mainly due to pileup (approximately 0.1% of the main peak.

Problems:

PTB has put up a firewall that does not allow incoming connections and is causing trouble with our P.C. based mail programs. We are asking the computer specialist to help us resolve this problem.

NOTE: This page copied from the email posted and edited in format only.