When Conway and the rest of the UEC board decided to establish the award, there was no question what to name it. "Everyone looked at each other and simultaneously said, 'Alvin,'" noted Conway. Tollestrup, for his part, was thrilled to lend his name to such a cause.

"I wish we could give many more of these awards," said Conway. "It was a difficult choice last year and we expect the same this year."

The deadline for nomination is April 30, and the winner will be notified by May 31. The winner will be invited to present the work in a talk at the annual Fermilab Users' Meeting, and will receive a certificate of recognition and a check for $3000.
more information

Liquid nitrogen is used to cool the cryostats that maintain the Visible Light Photon Counter chips at a temperature of 9 kelvins near the DZero collision point. But the flow rate left some of the liquid nitrogen unvaporized, producing exhaust and vaporization in a large vertical heat exchanger outside the DZero Assembly Hall, and creating exhaust backpressure in the system.

Engineer Terry Tope of PPD Mechanical Process Engineering, assigned to the problem by group leader Rich Schmitt, found that recovering the liquid from the exhaust would lead to significant savings. Tope consulted D-Zero engineer Russ Rucinski, designing a phase separator vessel with Bill Cyko and Pat Poll to recover liquid while allowing gas to exhaust. Liquid from the phase separator vessel was pumped back into the cryostat supply.

Designer Jack Mateski designed the necessary piping spools and fitted them into a space already crowded with cryogenic pipes, valves, and vessels. Technician Bob Barger installed the separator vessel and pump, and fabricated the necessary piping. Dan Markley implemented the controls hardware and software, working with Mike Sarychev to commission the system and tune the controls.

With the liquid recovery, the increased flow rate to the cryostat has lowered the liquid nitrogen intercept temperatures, reducing the VLPC cryostat heat load by 4% and producing a 16% increase in the operating margin for the helium refrigeration plant.