Liquid Argon Purity Monitor Testing Bonnie Weiberg TRAC Program Summer, 2015 ICARUS clone made at FNAL (S. Pordes - FNAL May 13th 2006)

Purpose To compare the Cathode and Anode signals for the three quartz fibers bundled together vs. each one individually To measure the signal difference when an extension fiber was added via a connection through a PEEK coupler.

Experimental Setup Purity Monitor Diagram Optical Fibers are made of Quartz, surrounded by A Polyimide buffer. The Cathode is gold plated aluminum.

Experimental Setup Xenon Flash lamp Flash lamp is Newport/Oriel Model 6427 Xe, 3x2.5 mm Large Bulb, 5J, 60W, 9 ms Pulse width, 60Hz Flash lamp Note that Au Work function is 5.1eV λ < 250nm to extract an electron

Experimental Setup Oscilloscope, Low and High Voltage Arm provided by Dr. Alan Hahn.

Experimental Procedure After setting the Xenon Flash Lamp to 5000 mJ and 1 Hz, I adjusted the Cathode voltage to -100 Volts, and the Anode voltage to 400 Volts, producing an electric field of 500 Volts. I inserted the three fibers into the fiber holder and when they were against the flash lamp, I recorded the peak signals for both the cathode and anode. I repeated this procedure five times, removing the fibers completely, then reinserting them into the holder. I repeated the above procedure for each of the three individual fibers, five times each.

Experimental Procedure Screen shot of the Oscilloscope

Experimental Data Data Collected on June 26, 2015:

Experimental Data June 26, 2015 Continued:

Experimental Data Data Collected on June 30, 2015:

Experimental Data June 30, 2015 Continued:

Experimental Data After attaching a 1 foot fiber segment to fiber one using a PEEK coupler, the following data was collected:

Experimental Results Based upon the two days of testing, fiber one produced the strongest cathode and anode signal of the three fibers. The highest peak value of mV was measured on the first day of the purity monitor being under vacuum at 6.5 x torr. Adding a fiber extension using a PEEK coupler and set screws decreased the cathode signal by a factor of 20. Using optical grease inside the coupler did not help the signal strength.

Conclusions The data collected is much lower in voltage compared to data collected by Dr. Hahn in November, Using a coupler produced a decrease in the cathode and anode signals. Further investigation of the cleaving process of the Quartz fibers, including the possibility of removing the polymer protective coating, is needed to see if the signals can be amplified.

References 1. “Purity Monitor - Description and Experience at Fermilab.” S. Pordes - FNAL May 13th “Preliminary Results from Scan of Flash Lamp Radiation Pattern with a Quartz Fiber Mounted on an Adjustable three axis table.” AAH + MR, November 20, Polymicro Technologies Silica/Silica Optical Fiber FV Specification Sheet, Molex, 2013.