Report of the SEM Calibration at NIST October 21 1999 - November 9 1999

A.R. Jones R. Vest & D. McMullin

11 April 2000

 

 

Introduction and Setup

After Sounding Rocket flight (US36.181.) on 18 August1999 the SEM was prepared for calibration at NIST. The SEM had been stored in a dry Nitrogen sealed bag after flight, and was prepared for transport by pumping in an Ion Pump chamber for one week prior to shipment, and then sealed in dry nitrogen for transport to NIST.

Thursday October 21 1999

The SEM instrument was mounted on the carrier for Beam Line 9 (BL9) in the horizontal position. The top cover of the SEM was removed as was the aperture assembly and the front assembly.

The filter was orriented with the serial# in the lower RH corner and the grating serial# in the upper LH corner as viewed from the front of the SEM.

The wiring harnesses were connected and a ground strap was placed between one of the feedthrough BNCs to the chassis of the SEM. Shorting the BNC to the structure case reduced the noise from about 7cps to about 3cps.

The pumps were started to pump down the system

Friday October 22 1999

The data collection system for BL9 has changed from a microVax to a Macintosh G3. Work on the interaction between CALROB2.BAS (on our PC) and the Labwindows system on the Mac produce and interactive system that displays the QE in real time.

Sunday October 24

Write NISTSCAN.BAS for the PC to provide autonomous, highresolution wavelength scans on BL9 in conjunction with the MacG3 controller.

 

Calibrations and Scans

Monday October 25

Chamber pressure is at 5¥10-8 T

 

Alignment

X Q Y F
0.4635 0.9905 0.9415 0.5000

10:50 Start Calibration: T=148: Grating 0°

Calibration data sets:

1A

1B

1C (wavelength scan problem in 1C)

12:10

Scan data sets

2A (340 —170 Å, step 1Å)

2B (340 —170 Å, step 3Å1

14:30 New Beam

3C (340 — 170Å, step 3Å)

Calibration data set

4A (304Å point added)

note: We still get ‘turn-up’ at small wavelengths in the calibration runs, not as much in the scans. Rob modified the scan program on the mac to measure the monitor dark for every scan position.

Scan data set

5A (340 — 160 Å step 3Å) (Monitor darks)

6A (340 — 160 Å step 5Å) (Record fluxes)

note: We seem to be seriously photon flux / statistics limited shortward of 200Å, so for calibrations it is probably a good idea to increase nsample (currentlt 20).

Try with an e-beam energy of 1331MeV (was 180 MeV)

Scan data set

7A (340 — 160Å step 5Å) (Beam energy 331 MeV)

Tuesday 26 October

9:49 Beam energy 180 MeV

Scan data set

1A (340 — 170 Å step 5Å)

Calibration data set

2A (BNC ground strap on)

2B (BNC ground strap off)

Start doing grating scans: 0.1° corresponds to a change in micrometer position of 0.0144".

Alignment

X Q F Y
0.41785 1.0049 0.9415 0.5000

Scan data set

3A (340 — 175 Å step 5Å: Q = + 0.1 °)

Alignment

X Q F Y
0.3826 1.0193 0.9415 0.5000

Scan data set

3B (340 — 175 Å step 5Å: Q = + 0.2 °)

Alignment

X Q Y Y
0.35114 1.0337 0.9415 0.5000

Scan data set

3C (340 — 175 Å step 5Å: Q = + 0.3 °)

13:15 New Beam

Alignment

X Q F Y
0.49537 0.9761 0.9415 0.5000

Scan data set

3D (340 — 175 Å step 5Å: Q = - 0.1 °)

Alignment

X Q F Y
0.53325 0.9617 0.9415 0.5000

Scan data set

3E (340 — 175 Å step 5Å: Q = - 0.2 °)

 

Alignment

X Q F Y
0.57133 0.9473 0.9415 0.5000

Scan data set

3F (340 — 175 Å step 5Å: Q = - 0.3 °)

note: connect a BNC T into the channel 2 data line, and use a frequency counter for alignment. This saves having to move the GSE box every time to the BL. We checked that it has no effect on the recorded counts or noise.

Alignment

X Q F Y
0.4635 0.9905 0.9415 0.5000

Calibration Scan data set

4A (340 — 175 Å step 5Å: Q = 0.0 °)

Calibration data set

4B

Calibration Scan data set

5A (360 — 260 Å step 5Å)

Scan data set

5B (360 — 260Å step 5Å)

Calibration data set

6A (repeat 5 measurements at 290 Å)

Scan data set

6B (repeat 5 measurements at 290 Å)

note: The discrepancy between the displayed scan and calibration values is that when I send the data from the PC to the mac I do not subtract the dark counts. Modify the program to send dark subtracted counts to the Mac.

Calibration data set

7A (repeat 5 measurements at 290 Å)

This now gives good agreement wirh 6B

Note: the problem does not effect the data recorded on the PC, ONLY the display on the Mac

Wednesday 27 October

Scan X micrometer to determine beam width. Center was at 0.46350. Use frequency counter to make measurements and alignments.

Micrometer position

counts
0.250 25
0.30 38
0.325 277
0.350 812
0.375 1438
0.400 2100
0.425 2689
0.450 3059
0.475 2900
0.500 2410
0.525 1755
0.550 1147
0.575 505
0.600 155
0.625 38
0.650 27
0.70 26
   
dark 25
FWHM 4.034mm
Base 7.1mm
Beam Size 3.1mm

 

Alignment

X Q F Y
0.43554 0.9970 0.9415 0.5000

Scan data set

1A (340 — 175 Å step 5Å: Q = + 0.05 °)

Alignment

X Q F Y
0.38060 1.0193 0.9415 0.5000

Scan data set

2B(340 — 175 Å step 5Å: Q = + 0.2 °)

 

Break Vacuum and rotate the SEM 90° CCW

Rotate the F micrometer 90° to make it easier to read.

 

Alignment

X Q F Y
0.5000 0.9587 0.4973 0.9671

Calibration data set

3A (dark counts high because the SEM does not shield the Ion pump)

3B

Scan data set

4A (340 — 175 Å step 5Å: F= + 0.0 °)

Alignment

X Q F Y
0.5000 0.9587 0.57183 0.9959

Scan data set

4B (340 — 175 Å step 5Å: F= + 0.2 °)

Alignment

X Q F Y
0.5000 0.9587 0.42114 0.9383

Scan data set

4B (340 — 175 Å step 5Å: F= - 0.2 °)

Thursday 28 October

Alignment

X Q F Y
0.5000 0.9587 0.53647 0.9815

Scan data set

1A (340 — 175 Å step 5Å: F= + 0.1 °)

Alignment

X Q F Y
0.5000 0.9587 0.46001 0.9527

Scan data set

1B (340 — 175 Å step 5Å: F= - 0.1 °)

Alignment

X Q F Y
0.5000 0.9587 0.49769 0.9671

Calibration data set

2A (340 — 175 Å step 5Å: F= 0.0 °)

 

Break Vacuum

Rotate Grating; serial # is now in lower left viewed from front.

New Beam

 

Alignment

X Q F Y
0.5000 0.9573 0.9652 0.4946

Calibration data set

3A (340 — 175 Å step 5Å: F= 0.0 °)

note: Channel 3 efficiency is back!

Scan data set

3A (340 — 175 Å step 5Å: F= 0.0 °)

Alignment

X Q F Y
0.5000 0.9573 0.9940 0.57128

Scan data set

4A (340 — 175 Å step 5Å: F= +0.2 °)

Alignment

X Q F Y
0.5000 0.9573 0.9573 0.57128

Scan data set

4B (340 — 175 Å step 5Å: F= +0.2 °) (check alignment)

Alignment

X Q F Y
0.5000 0.9573 0.9364 0.42097

Scan data set

4B (340 — 175 Å step 5Å: F= -0.2 °)

Beam Geometry measurement Y-Scan

Micrometer position

counts
0.350 4
0.375 8
0.400 47
0.425 88
0.450 128
0.475 153
0.500 153
0.525 151
0.550 115
0.575 72
0.600 33
0.625 6
0.650 5
   
dark 4
FWHM 3.854 mm
Base 6.167 mm
Beam Size 2.313 mm

 

Friday 29 October

Break vacuum and rotate SEM to horizontal position

Reinstall in BL9 and pump

Friday AM. Is used for maintainance of the ring.

 

Alignment

X Q F Y
0.4742 0.98115 0.9575 0.5000

Calibration data set

1A (340 — 175 Å step 5Å: Q = 0.0 °)

Scan data set

2A (340 — 175 Å step 5Å: Q = 0.0 °)

Alignment

X Q F Y
0.42240 1.0100 0.9575 0.5000

Scan data set

2B (340 — 175 Å step 5Å: Q = +0.2 °)

Alignment

X Q F Y
0.54748 0.9524 0.9575 0.5000

Scan data set

3C (340 — 175 Å step 5Å: Q = -0.2 °)

 

Beam Geometry measurement X-Scan

Micrometer position

counts
0.275 2
0.300 4
0.325 18
0.350 47
0.375 86
0.400 123
0.425 146
0.450 151
0.475 138
0.500 109
0.525 71
0.550 34
0.575 11
0.600 3
0.625 2
   
dark 1.5
FWHM 3.917 mm
Base 6.438 mm
Beam Size 2.521 mm

Break Vacuum and rotate SEM 90° CW

Pump

Monday November 1 1999.

Alignment

X Q F Y
0.500 0.9791 0.9740 0.5022

Calibration data set

1A (F = 0.0 °)

Scan data set

2A (340 — 170 Å step 5Å: F = 0.0 °)

Alignment

X Q F Y
0.500 0.9791 1.0028 0.57720

Scan data set

2B (340 — 170 Å step 5Å: F = +0.2 °)

Alignment

X Q F Y
0.500 0.9791 0.9452 0.42574

Scan data set

2B (340 — 170 Å step 5Å: F = -0.2 °)

Beam Geometry measurement Y-Scan

Micrometer position

175 Å
 304Å
0.350 2 2
0.375 2 2
0.400 30 10
0.425 67 34
0.450 103 60
0.475 132 85
0.500 135 95
0.525 134 95
0.550 109 88
0.575 71 62
0.600 35 38
0.625 5 12
0.650 2 2
0.675 2  
     
dark 2 2
Grating 3.867 mm 3.812 mm
Beam Size 2.309 mm 2.313 mm

 

Break Vacuum

Remove grating/filter assembly

Remove Solar wind deflector assembly

Alignment

X Q F Y
0.500 0.9791 0.9740 0.5022

Calibration data set

1A (F = 0.0 ° Channel 2 only – no grating)

Beam Geometry measurement Y-Scan, 304 Å

Micrometer position

counts
0.325 10
0.350 11
0.375 147
0.400 380
0.425 620
0.450 863
0.475 997
0.500 1016
0.525 1030
0.550 1042
0.575 1030
0.600 793
0.625 540
0.650 285
0.675 46
0.700 13
0.725 12
   
dark 7
FWHM 5.40mm
Base 8.075 mm
Beam Size 2.675 mm

 

Break Vacuum

Rotate SEM to Horizontal

No grating, filter or Solar wind deflector assembly

Alignment

X Q F Y
0.500 0.98115 0.9575 0.5022

Beam Geometry measurement X-Scan, 304 Å

Micrometer position

counts
0.250 10
0.275 20
0.300 190
0.325 730
0.350 1580
0.375 2530
0.400 3400
0.425 4000
0.450 4200
0.475 4185
0.500 4040
0.525 3670
0.550 2970
0.575 2100
0.600 1230
0.625 535
0.650 136
0.675 38
0.700 28
0.725 23
0.750 18
0.775 15
0.800 12
0.825 10
   
dark 7
FWHM 5.334mm (diode)
Base 8.367 mm
Beam Size 3.033 mm

 

Break Vacuum

Reinstall graing in ORIGINAL orrientation

Replace deflector assembly

SEM in Horizontal poition

Start pumps

Reset date/time on DAQ PC.

Tuesday November 2 1999.

Alignment

X Q F Y
0.46854 0.9797 0.95055 0.5000

Beam Geometry measurement X-Scan

Micrometer position

counts
0.300 1
0.325 7
0.350 27
0.375 55
0.400 83
0.425 110
0.450 132
0.475 135
0.500 117
0.525 90
0.550 62
0.575 34
0.600 13
0.625 3
0.650 2
0.675 1
   
dark 1
FWHM 3.975 mm (diode)
Base 7.075 mm
Beam Size 3.10 mm

Calibration data set

1A (Q = 0.0 °)

Scan data set

2A (340 — 170 Å step 5Å: Q = 0.0 °)

Break Vacuum

Move SEM to vertical

New Beam

Note: It is Very windy outside, and the risk of a power surge forces us to dump the beam and call it a day.

Wednesday November 3 1999.

Note: We are trying to find the ‘excess’ dark counts that give the low wavelength tails.

Change the wavelength file to look at only: sparse wavelengths:

330, 304, 290, 270, 215 & 175 Å

Run with No BEAM! Open BL valves set up exactly as normal but disconnect shutter

Calibration data set

1A (No beam, shutter closed, Ion pump open, GND strap on, sparse l set, Vertical (not alligned))

Note: The Kiethley 617 (diode monitor) does not give the same reading for signal / dark even though nothing changes physically. Run the 617 manually, it seems to be just statistical variation.

Calibration data set

1B (No beam, shutter open, Ion pump open, GND strap on, sparse l set, Vertical (not alligned))

1C (No beam, shutter changing, Ion pump open, GND strap on, sparse l set, Vertical (not alligned))

1D (same as 1C)

note: No systematic effects seen

Ion pump closed, noise goes down.

Calibration data set

2A (No beam, shutter changing, Ion pump closed, GND strap on, sparse l set, Vertical (not alligned))

note: no assymetry seen

Calibration data set

3A (No beam, shutter changing, Ion pump closed, GND strap off, sparse l set, Vertical (not alligned))

Inject beam

Rough Vertical alignment

Shutter normal

Remove external frequency counter ground

Calibration data set

4A (beam, shutter changing, Ion pump closed, GND strap off, sparse l set, Vertical, frequency counter disconnected)

4B (beam, shutter changing, Ion pump closed, GND strap off, sparse l set, Vertical, frequency counter connected)

4C (beam, shutter changing, Ion pump open, GND strap off, sparse l set, Vertical, frequency counter disconnected)

4D (exactly the same as 4C, but don’t restart control program)

4E (beam, shutter changing, Ion pump open, GND strap on, sparse l set, Vertical, frequency counter disconnected – transient as GND connected)

Note: no ‘tail’ seen in any of the 4A — 4E data sets!

Full SEM Vertical alignment

Alignment

X Q F Y
0.5000 0.9788 0.9764 0.51867

Calibration data set

5A (sparse l)

5B (full l)

Note: no ‘tail’ seen in the 5A,B data sets!

 

Dismount SEM from BL9, return grating to ‘high efficiency’ position. Pack in dry nitrogen and ship back to USC.

 

Appendix A; Beam Geometry Measurements

 

 

 

SURF iii Beamline-9 beam size measurements using SEM

Andrew Jones (USC), Rob Vest(NIST)

October 1999

 

 

The linear size of the beam from the SURFiii facility at BL-9 was measured by SEM by linear scans of the SEM channel-2 (0-order) detector over the beam. The SEM filter and grating were left in the instrument for the measurements.

The response of the SEM to linear scans is roughly trapizoidal, as expected for scanning a finite size beam over an aperture (the SEM grating). The size of the base of the trapezoid is B + W, where B is the beam size, and W the aperture width.

 

SEM Data

Horizontal Scan

inches counts mm counts — dark

0.250 25 6.3500 0

0.300 38 7.6200 13

0.325 277 8.2550 252

0.350 812 8.8900 787

0.375 1438 9.5250 1413

0.400 2100 10.160 2075

0.425 2689 10.795 2664

0.450 3059 11.430 3034

0.475 2900 12.065 2875

0.500 2410 12.700 2385

0.525 1755 13.335 1730

0.550 1147 13.970 1122

0.575 505 14.605 480

0.600 155 15.240 130

0.625 38 15.875 13

0.650 27 16.510 2

0.700 26 17.780 1