Emittance Probe 1 (side)Distance from slit to detector: 4.470 inches

Detector with multiple collectors

Expected collector width based on individual measurements: 0.008 (8 mils)

1 copper strips and 1 Kapton strip make up a collector

Width of 1 copper strip: 6 mils

Width of Kapton: 2 mils

Average Collector Width: 9 mils

The detector is comprised of 22 collectors plus 1 additional Kapton strip

The total detector width as measured: (aprox.) 0.201

The average collector width is defined as the detector width – the width of 1 Kapton strip/ number of collectors [(0.201-.002)/22]

Angular Resolution: (2 mrad)

~ Sin() = ave. collector width / distance from slit

Measured distance from shield to detector : (aprox.) 1.72 inches

Emittance Probe 2 (top) Distance from slit to detector: 4.525 inches

Detector with multiple collectors

Expected collector width based on individual measurements: 0.008 (8 mils)

1 copper strips and 1 Kapton strip make up a collector

Width of 1 copper strip: 6 mils

Width of Kapton: 2 mils

Average Collector Width: 8.8 mil

The detector is comprised of 22 collectors plus 1 additional Kapton strip

The total detector width as measured: (aprox.) 0.196

The average collector width is defined as the detector width – the width of 1 Kapton strip/ number of collectors [(0.196-.002)/22]

Angular Resolution: (1.95 mrad)

~ Sin() = ave. collector width / distance from slit

Measured distance from shield to detector : 1.72 inches (from probe 1)

Probe 1 and Probe 2 Output Channel mapping

Conversion To current Channels20 01 23 45 67 89 1011 1213 1415 1617 1819 20

Probe pin numbers21 12 34 56 78 910 1112 1314 1516 1718 1920 21

Outer most

Inner mostShield Pin 22

Pin 23,24 are not usedPin 25 grouned

Basic Operation• Probes 1-4 all use the same amplifiers. Thus each time a probe is

used the correct cable in the back of rack LE1-RR2-10 needs to be connected to the sample and hold unit.

• The ACNET channels are:HVEM00 through HVEM20

• The motor control channels are:PROBE1 through PROBE4

• Probes 1 and 2 cannot both be in the beam at the same time because they occupy the same space. Thus they are interlocked such that one must be in the “out” position before the other can be inserted. Similarly for probes 3 and 4.

• To run Probes 3 and 4 the safety system beam stops need to be out. This means the Linac needs to be secured. However you do not need to accelerate beam because these probes are at the front of Tank 1.

• A +700 volt bias on the shields seems to yield the “cleanest” signal however this means that secondary electrons dominate the signal. Beware! The production of secondary electrons on surfaces is very dependant on the incident angle of the primary ion. See the next slide for a rough correction.

Probe2 Secondary Electron Correction

For additional information on secondary electron emission see Huashun Zhang, Ion Sources, p. 12-13, 1999.

The secondary electron yield (SEY) is the number of liberated electrons per incident particle, in this case negative hydrogen. SEY change nonlinearly with the incident particle energy and is dependant on the incident angle scaling roughly as the secθ of the the incident angle.

The probable signal adjustment for Probe 2 is shown here. To correct the probe signal multiply by the values given here.

Probe 1 Secondary Electron Correction