[time-nuts] MINOS Status on Measuring Neutrino Velocity

[Marvin Marshak]

The MINOS Collaboration has made progress in its effort to use the Fermilab to Soudan MN neutrino beam to investigate the effect reported by the OPERA Collaboration of neutrinos travelling faster than the speed of light. The current MINOS methodology has two parts: (1) to retrospectively analyze data collected since 2005 with timing established by Truetime XL-AK GPS units and (2) to use new data to be collected during March and April 2012 with significantly enhanced timing instrumentation. The retrospective analysis will include considerably more data and improved analysis algorithms, compared with the observations published by MINOS in 2007.

In this email, I will focus on the new instrumentation. MINOS now has three timing stations. The first station is located at a point called MI-60, which is at the Fermilab Main Injector in Batavia IL, an accelerator that produces the proton beam that eventually results in the neutrino beam. The MI-60 station monitors the antecedent proton flux as a function of time. The second station is located in the MINOS Neutrino Near Detector, which is approximately 1 km from the proton target. The third station is located at the MINOS Neutrino Far Detector in Soudan MN, approximately 735 km from the proton target. Each timing station includes an HP5071A cesium clock, installed with help from the U.S. Naval Observatory; a Novatel dual-frequency code and carrier phase GPS receiver, modified by and installed with help from NIST; and multiple Agilent 53230A time interval/frequency counters. Each station also has ancillary hardware, including distribution amplifiers, optical fiber links, temperature stabilization chambers and monitoring computers. Each station also has instrumentation to measure and monitor changes in propagation delays in the various cables and optical fiber links, particularly the long ones between surface GPS receivers and the deep underground detectors. An additional HP 5071A will be used for round trip travel between Fermilab and Soudan. The clock synchronization between the two ends of the beam will also be checked using other methods with help from USNO and NIST. I expect to describe these methods later when arrangements are more complete.

These stations enable three inter-station measurements:
• MI-60 to Near Detector: Most distance travelled by charged particles; should be very close to speed of light.
• MI-60 to Far Detector: Almost entirely neutrino propagation delay.
• Near Detector to Far Detector: Entirely neutrino propagation delay.

We have just started operating the HP5071A cesium clocks in the last few days and are interested in suggestions for optimal operation and monitoring of these units.   The HP5071As can be controlled and read out via a serial connection, and
the device has many operating parameters it can report. Which of those parameters are most useful for long-term monitoring of the clock stability? Are there subtle problems in using these units?

The next few months should produce interesting results and I will try to keep the list informed on progress.


Marvin L. Marshak
College of Science and Engineering Professor
Morse-Alumni Professor
University of Minnesota
116 Church Street SE
Minneapolis MN 55455  612-624-1312     612-624-4578 (fax)