IR 2 Vacuum Update

M. Sullivan for PEP-II team

For the 2e34 meeting of Feb. 15, 2006

• Orientation

• A look at some of the gas squirt events

• NEG heating events

• Summary

Typical event from Feb 5th

LER HER

2.29

1364

122

LER frangible link

Detector

0

2.25

993

Support tube end bellows

NEG pump

Backward Q2 NEG

Forward Q2 NEG

0 0.08

Another typical event from Feb 5th

LER HER

0.54

1653

27

LER frangible link

Detector

0

0.82

198

Support tube end bellows

NEG pump

Backward Q2 NEG

Forward Q2 NEG

0 0.07

Small numbers have larger baseline subtraction errors

Vacuum events with single ring LER on Sat. morning Feb 11th

Vacuum spike

Big vacuum spike

100 nTorr squirt

Vacuum spike event at 11:50 on Feb 11th

2300 mA in LER only

LER HER

2.44

7950

16.9

LER frangible link

Detector

0.34

4.32

1413

Support tube end bellows

NEG pump

Backward Q2 NEG

Forward Q2 NEG

0 0.60

Squirt event at 11:51

LER HER

0

334

0.29

LER frangible link

Detector

0

0

1171

Support tube end bellows

NEG pump

Backward Q2 NEG

Forward Q2 NEG

0 0.07

The highest vacuum spike event at 11:57 on Feb 11th

2446 mA in LER only

LER HER

17.2

3830

225

LER frangible link

Detector

1.16

9.2

3672

Support tube end bellows

NEG pump

Backward Q2 NEG

Forward Q2 NEG

0 2.05

Big air event when we opened a valve

LER HER

240

0

3440

14

LER frangible link

Detector

24

81

1360000

Support tube end bellows

479

NEG pump

Backward Q2 NEG

Forward Q2 NEG

10000 nTorr squirt (no beam)

LER HER

1.01

0

10.1

LER frangible link

Detector

0.19

0.61

9125

Support tube end bellows

NEG pump

Backward Q2 NEG

Forward Q2 NEG

0.07 1.57

Argues that the 3027 gauge sees too much pressure

10000 nTorr squirt (with beam)

LER HER

1.01

0

10.3

LER frangible link

Detector

0.19

0.61

8720

Support tube end bellows

NEG pump

Backward Q2 NEG

Forward Q2 NEG

0.95 1.29

Argues that the 3027 gauge sees too much pressure

Heating forward Q2 NEG pump

60 nTorr

Forward Q2 NEG heating with beam

LER HER

0.38

72

5.1

LER frangible link

Detector

0.08

8.9

60

Support tube end bellows

NEG pump

Backward Q2 NEG

Forward Q2 NEG

0 0

The 8020 pump sees too much pressure

Heating up the forward Q2 NEG

Luminosity went down when we added gas.

The decrease is noticeable at a pressure of about 30 nTorr

Traced to the HER vertical spot size increasing.

Luminosity restored as the pressure goes down.

Heating up HER Q5 NEG (8020) on the forward side of the detector

Detector backgrounds remain low

380 nTorr

Heating of 8020 NEG today -- Feb 15th

LER HER

0.42

56

2.1

LER frangible link

Detector

0

380

20.6

Support tube end bellows

NEG pump

Backward Q2 NEG

Forward Q2 NEG

0 0.29

HER 8020 NEG

• When we heated up the HER forward side NEG (8020) we saw the HER vertical spot size increase and the lumi decrease when the gas pressure got up to about 30 nTorr

• The gas is predominately H2

• As the gas pressure increased further the HER vertical spot size got smaller again and the HER went horizontally unstable

• We lost the beams on a radiation abort, however there was no vacuum spike and the pressure was coming down since we had turned off the heater about 2 min earlier

Summary

• The pressure squirts argue the source is closer to the IP from the 3027 gauge because the pressure seen at the 3027 gauge is too high

• The heating of the forward Q2 NEG and the HER 8020 NEG argue the vacuum spikes are between the detector and the Q2 NEG (could be in the location of the Q2 NEG)

• Unfortunately not yet able to rule out the support tube