LER thermal outgassing is back again with us

• Significant increase in East Diamond signal since May 12, ~3 pm due to thermal outgassing in two pumps VP3044, VGCC3027

• Happened one day before the last LER current step (2400 mA on May 13)

• Due to HER current increased from 1.3A to 1.4A• As in March, change associated with pressure

AND sensitivity variations in these pumps• Seen also in DCH and DRC

One month history of LER and Diamond East

LER

East Diam

April 17

May 18

May 12

Extra heating due to HER increase (thanks to Witold for pinting this out!)

HER increased from 1.3 to 1.4 A

From 3 pm onwards

Pressure variations in VP3044 and VGCC3027

VP3044 VGCC3027

VP3075VP3147

Detailed history of May 12

LER

VP3044

VGCC3027

East Diam

Time in hours

0 12 24

Detailed history of May 13

LER

VP3044

VGCC3027

East Diamond

Also affects DCH and DRC(not corrected for HER increase)

DCH DIRC 0

600

1000+20 %

+20%

One month History April 17_May 18 One month History April 17_May 18

It is also thermal outgassing in DCH and DRC

DCH DRC 0

Time in hours Time in hours

More evidence that DCJ is outgassing

and NOT neutronsLER/HER/LUMI

DCH

Neutrons

Diam East

May 18

7 pm to 11 pm

Summary of May 12-13 for DIAM E

All variables normalized to 1 on MAY 18 0 am

Time in hours

DIAME

LER

VP3044

VGCC3027

HER

Summary for May 12-May 21

DIAMELERVP3044VGCC3027HER

Summary of May 12-13 for DRC and DCH

All variables normalized to 1 on MAY 18 0 am

Time in hours

LER

VP3044

DRC0

DCH

HER

Diamond East is perfectly described with two pumps vP3044

and VGCC3027

May 11 6 pm to Midnight

Diam E

VGCC3027

VP3044

14

After the start of outgassing

May 13, 8 pm to Midnight

14

25

Almost doubling of DIAME

Still true later on

May 17

3am to Midnight

The coefficients, normalised to 1 on May 10

VP3044VGCC3027

VP3075 VP3147

Days in May Days in May

Evolution of pressures and DIAM-E sensitivity coefficients

Sensor Pressure change

Coefficient

change

Total change

VP3044 X 1 X2.5 X2.5

VGCC3027 X3.5 X0.6 X2.1

DiamE x1.65

Conclusion

• Significant increase (x1.65) of DIAME since May 12 due to thermal outagassing in VP3044 and VGCC3027

• Caused by the HER current increase from 1.3A to 1.4A• Affects also DCH and DRC• Pressure AND sensitivity variation in both pumps

– VP3044 sensitivity x 2.5– VGCC3027 reduced by a factor 2 !– Evidence of VP3044 pressure reduction with time

• Will be interesting to correlate with the many new temperature sensors

Pressure spike on May 22

Pressure spike on May 23

BABAR dead time driver

East Diamondrecent week