conditioning the new bag day 1: 25 feb 2008. particle number concentration (wcpc 3786) lights on at...

Conditioning the new bag

DAY 1: 25 Feb 2008

Particle number concentration (wcpc 3786)

Lights on at 15:58

DMPS after one hour of lights on

Mass = 11 ugm-3 (density 1), mode about 52 nm

Status at the end of day 1 of cleaning

• After about 2 hours of lights on, 17 ugm-3 of mass (DMPS) were formed in the chamber and particle size mode was about 70 nm. The bag was flushed and post exp procedures were perfumed. The bag was left full of ozone overnight.

New bag Cleaning: Day 2Tuesday 26 Feb 2008

• Started at 08:50. Bag had 6500 p/cc.

• Flushed the bag

• Started pre-exp procedures

Particle number dropped to 40p/cc after the first flush

First fill is complete: 17p/cc

Completed 3 flush/fill cyclesBag is now in flushed position and being tested for leaks…started test at 09:45 and there was a small increase in number but not close to our

previous problem!

Ozonolysis increased number dramatically! Lights were turned on at 10:17

Mass and number after 50min of lights on

9.8 ugm-3 and 1.2e5 p/cc

CPC problem!!

• 16:45 lights off (i.e. cleaned for more than 6 hours)

• Post-exp procedures started

• Bag was left full of O3 overnight

18:11Post-exp procedure completed. The Ozone box thinks there is 720 ppb of O3 in the bag

New Bag Cleaning

Day 3: 27 Feb 2008

• Bag was left full of ozone over night

• Flushed the bag and started the pre-exp procedures

• Completed 4 fill/flush cycles

• Ozone at the beginning is 1.2ppm

Lights on at 10:09

Yellow error sign saying CPC is still in warm up mode (flow range and temp errors)

Last scan before lights on measured 13 ugm-3!! (note the long DMA scan!!)

First scan after lights on measured 77 ugm-3!! (note the long DMA scan!!)

DMPS appears to be wet and arcing at high voltages.. The reported mass is wrong

DMPS, mass=9.08, 1 hour after lights on, no arcing on this scan

11:49

End of day 3

• Lights were switched off after 5 hours

• Flushed the bag

• Performed post-exp procedure

• Last fill was done manually with O3 pulsing

• Bag was left with 870 ppb of O3 overnight

C:\elena\Tank_Feb_08

New Bag Cleaning

Day 4: 28 Feb 2008

First background Exp

• Flushed the bag from the overnight o3 fill

• Pre-exp procedure to cycle fill/flush for 4 times

• Final fill via humidifier and inject NOx

• Humidifier is NOT working!! Change of plans

• Another harsh cleaning day (O3 + lights)

• 980 ppb O3 according to ozone box

Bag is flushed and still: note particle number is slightly increasing (could be mixing or small leak)

Most likely it is fresh nucleation! Do it again next time with doors closed

Immediate response to ozone

Response to lights (on at 10:49)

First 10 min after lights on

Fab!! It is now down to 2.3 ugm-3 after 1 hour of lights on

CPC problem appears to be coming back