Commissioning a Cosmic Ray Muon Detector for Cosmic Ray Radio Wave Research

Names: Brittany Crossen,  Ottawa High School, Ottawa, KS

Ardrian Tidwell, Insight School of Kansas, Olathe, KS

Research Teacher Mentor: James Deane, Ottawa High School, Ottawa, KS

Research Mentor: Prof. Dave Besson, University of Kansas, Lawrence, KS

Purpose: We are building apparatus to help us detect and characterize radio wave emission from cosmic ray impacts in the upper atmosphere and the particle showers they create. As part of this we learned how to use and operate a Cosmic Ray (Muon) Detector, or CR(M)D, for the purpose of detecting and analyzing showers produced by cosmic rays. The ultimate goal is to find the correlation between cosmic ray showers and cosmic ray generated radio waves. It is important to ensure that our system only triggers on events that are extremely likely to be muons from cosmic ray showers, and that the trigger rate is compatible with the radio digitization hardware.

Methods: we began with a partially assembled CRMD. Several issues were discovered, including a PMT which did not operate at the same frequency as the others at the same tube supply voltage. We were able to calibrate this tube at a higher voltage, and it seems to operate and gives expected results compared to the other tubes. We also spent some time familiarizing ourselves with the computer commands necessary to communicate with and control the various settings of the Digital Acquisition board (DAQ). However, the commands and language were eventually deciphered and new avenues of data acquisition were opened.

Several pieces of hardware were used jointly to achieve data collection, from the QuarkNet Data Acquisition Board (DAQ) to the individual detectors. We used Ubuntu linux and the SCREEN program to connect, control, and collect data from the DAQ. Some of the commands for changing settings on the detector were discovered in the process of troubleshooting.

Results: We have evaluated multiple paddle configurations and settings to properly trigger the radio receiver and radio data acquisition part of the experiment. However, further testing is needed to evaluate more configuations and determine optimal settings. For this reason, more data in different scintillator paddle configurations is being collected and analyzed to reduce the trigger rate to a frequency where the radio wave detector and acquisition system can operate (around 50 triggers per second).

We are adjusting the following variables: coincidence number, gate width (the time window during which the detectors need to be activated, starting from the first detector’s activation), threshold level (the “strength” of the signal from a detector), and the geometry of the detector paddles.

The project is still incomplete, as the best detection rate we have so far achieved has not met the goal detection rate. We also need to determine how well we are discriminating true cosmic ray shower events. Comparing our count rate at the paddle and DAQ configurations we have used, we think there may still be false detector signals.

Meaning to Larger Project: The CRMD is intended to be used with a radio wave detector and digitizing system. The CRMD will detect cosmic rays by their muon showers and create a focus period for the radio wave detector. Studying radio wave emissions may give us further insight into the origin and characteristics of the particles that are cosmic rays.

Future Research:
Continuing to adjust the settings and geometry of the detector to increase the discrimination and decrease trigger rate is necessary to be able to continue to the final goal of radio detection. The radio wave detector, antenna, and digitizer will need to be added to the experimental setup and calibrated. The CRMD triggering will signal the digitizer to trigger and potentially capture cosmic ray radio signals, the original and ultimate goal of the project.

Acknowledgements:
We would like to thank the following for their assistance during the course of this research:

• Josh Macy, Undergraduate, University of Kansas, Lawrence, KS

• Dave Hoppert, Fermilab, Batavia, IL

• Mark Adams, Fermilab, Batavia, IL