Status

• Vacuum Pressures (Experimental Chamber, Cluster Source) = 2.9 10^-7, 2.5 10^-6 mbar
• Spectrometer (Vacc, Vdrift, Lens) = +404,-4008, -3248 V
• Detectors (Ion, Elec) = -1900, + 3200
• Count Rates (DarkCounts e/i) = 10 Hz, < 1Hz

i) As a starting point the photon energy is set at 200 eV (Gap 40.33 mm) with slits around 10um. By monitoring the position of the light in the Scienta chamber, we find that the beam is 1-2 mm too low
ii) The count rates on the detectors are then (e/i)= 1kHz, < 1Hz.
iii) There is no current on the ion detector (see F7* - reads current monitor value - on the power supply) : the circuit is open HT cable or the ground cannot be plugged correctly. Ramp up…

U (V)	500 V	1000 V	1500 V	2000 V
I (uA)	12	28	41	57

The values for the count rates are :

• Light Off (e/i) : 10 Hz, 15Hz
• Light On (e/i) : 1kHz, 2kHz

The discriminator for the electron detector is too high !!???!!! The threshold is set using the dark count just above the "surge" due to noise (-500 mV). One should check it with an oscilloscope and compare the value with previous logbook.In this condition the dark count is around 350 Hz and the signal 2,5 kHz.

iv) The cluster source is partially blocked. With 7 bars (on the regulator) the pressure in the cluster chamber is around 6.10^-5 mbar. One should expect a 10^-3 down to 10^-4 mbar . Something inside the chamber makes mechanically the alignment very difficult. Perhaps par of the cooling system touch the aluminum cylinder ? The position of the translation rod is found to be good at 369 mm with a pressure of 2,1.10^-6 mbar in the spectrometer chamber.

• The working position : <369 mm
• The rest position <110 mm (in order to close the valve)

End of the shift

i) The cluster source produces small clusters with 8 bar at -10 C. See file ArgonDimer made with 30 min acquisition