Transmission Tests at Nevis

We have performed simple transmission tests in order to understand how the R5600 miniature PMT output looks like after several tens of meters of coax cable length.

Tools Used

500 ft (152m) of RG213 (Belden) coax.
Custom pulser to mimic PMT output.
5V regulated power supply
Pulse generator.

Input Pulse

Amplitude: 855 mV
tRise=1ns
FWHM=12ns
Pulse is 20mV from baseline after 40ns.
Pulse is 4mV from baseline after 50ns.

Output Pulse

Amplitude: 440 mV
Time from Baseline to Peak = 7ns
FWHM = 18ns
Pulse is 11mV from baseline after 80ns.
Pulse is 6mV from baseline after 96ns.
+/- 3ns from peak, pulse is reduced by 50mV (~10%).

Other Information

Custom Pulser Ref. DC voltage = 4V.
Input Pulse: step pulse from 0 to 5V.
Operating Frequency: 100kHz.
Cable Type = RG213/U (Belden, PN8267)
Cable Attenuation = 6.9dB per 100m (2.1 per 100ft) at 100MHz.
Cable Length = 500ft (152m)
Cable Price = $0.68 per ft (for the 500ft order) no connectors.
Connectors = RG8 BNC plug (Amphenol PN6775), $7 per connector.

Comments The pulse shaping due to the long cable is such that there is not enough "plateau" at the peak. So the pulse is sharp with a long tail. The new result from these tests is that using the PMT output alone (without some integrator etc) to drive the ADCs might lead to errors due to time jitters.