Flow rate

Fe55 with premixed 50/50 Ar/CO₂, New preamp and new HVB, ADC half-range, for a range of HV and (later) gas flow rate
From New HVB:

New preamp and HVB - max amplitude histo for 55Fe

New preamp and HVB - energy histo for 55Fe

Mixed 50/50 at 80 sccm total, less HV

max amplitude histo for 55Fe mixed 50/50 at 80 sccm

energy histo for 55Fe mixed 50/50 at 80 sccm

Mixed 50/50 at 40 sccm total - note the change in x-axis scale. The 2050V run was wrong initially, corrected 1340 Oct 27.

max amplitude histo for 55Fe mixed 50/50 at 40 sccm

energy histo for 55Fe mixed 50/50 at 40 sccm

Various gas flow rates at 1850V (left) and 2050V (right)

energy histo for 55Fe mixed 50/50 at 1850V

energy histo for 55Fe mixed 50/50 at 2050V

Events at 80 sccm total, 1850V (left) and 2050V (right)

energy histo for 55Fe mixed 50/50 at 1850V

energy histo for 55Fe mixed 50/50 at 2050V

Events at 40 sccm total, 1850V (left) and 2050V (right)

energy histo for 55Fe mixed 50/50 at 1850V

energy histo for 55Fe mixed 50/50 at 2050V

As above, zoomed in on pedestal... 80 sccm total, 1850V (left) and 2050V (right)

energy histo for 55Fe mixed 50/50 at 1850V

energy histo for 55Fe mixed 50/50 at 2050V

40 sccm total, 1850V (left) and 2050V (right) The little blip at ~ch 250 in the RH plot is an afterpulse, this is not noticeable at 2000V.

energy histo for 55Fe mixed 50/50 at 1850V

energy histo for 55Fe mixed 50/50 at 2050V

Premixed gas at different flow rates, cylinder -> small flowmeter -> CDC prototype.
I used the small flowmeter and the bubble count to very approximately match the flow rates to those from the mixer...

80sccm from the mixer ~ off the top of the small flowmeter ~ 1.9 ± 0.2 bubbles/s
40sccm from the mixer ~ small flowmeter measures 57 ± 2 ~ 1.1 ± 0.2 bubbles/s
estimated c. 20sccm from the mixer ~ small flowmeter measures 27 ± 2 ~ 0.25 ± 0.02 bubbles/s - the prototype used to bubble at about this rate before we cooked it.
estimated c. 10sccm from the mixer ~ small flowmeter measures 15 ± 2 ~ 0.04 ± 0.02 bubbles/s

The non-linearity between flowmeter readings and bubble rate implies that the prototype is leaking at or below 40sccm. At higher flow rates, non-linearity between mixer readings and bubble rate might be caused by the small flowmeter obstructing the gas flow.

1850V, amplitude (left) and energy (right)

amplitude histo for 55Fe premixed 50/50 at 1850V

energy histo for 55Fe premixed 50/50 at 1850V

1950V, amplitude (left) and energy (right)

amplitude histo for 55Fe premixed 50/50 at 1950V

energy histo for 55Fe premixed 50/50 at 1950V

2050V, amplitude (left) and energy (right)

amplitude histo for 55Fe premixed 50/50 at 2050V

energy histo for 55Fe premixed 50/50 at 2050V