Resources for Cosmic Ray Analyses Online

Cosmic Ray Analysis Opportunities

The QuarkNet Cosmic Ray e-Lab ( contains a large data set of cosmic ray events and analysis tools with which teachers can perform experiments with their classes in these remote-teaching times. Please contact Mark Adams for any assistance you need.


Note: A 5th analysis project was added on 6May20: Large Air Shower Arrays.

Note: The file list for the Shower study was updated on 16Jul20.

Note: The file list for the Clean Lifetime was updated on 19Feb21.


This note describes the analysis tools useful for muon rates over time, muon lifetime, muon speed experiment, and angular acceptance, as well as lists of appropriate files compiled by Cosmic Ray Fellow Nate Unterman. Analyses are supported by “Tutorials” and “Step-by-Step Instructions” in the Resources page in e-Lab under the Library/Resource tabs. Two paths to take with e-Lab are described.


First, the Normal analysis path – select an analysis, pick a file, run the analysis, and create plots and posters.


The second direction is a set of slightly Simpler measurements (particularly for muon speed), however, many data files collected under stable conditions are listed, so that you can assign the same type of analysis to each student analyzing their own data file and discuss individual and combined results.


1. Muon Lifetime – A muon triggers the DAQ. The analysis searches for an electron candidate that is simply a second, later hit in one of the counters hit by the muon. The result is a frequency distribution of the time between the electron candidate and the muon. Use of the Simple and Normal paths are the same.


Expert notes:

  1. Most lifetime data is collected with large gates (~30 microseconds) so the electron hit occurs later in the event triggered by the muon. In other situations (e.g. DAQ 6234) a short gate (200 ns) is used so the electron must satisfy the hardware trigger separately.
  2. In the analysis command section use the defaul 1-fold coincidence. Avoid selecting 2-fold coincidence for the electron because the hard-wired cuts reject data unpredictably.

2. Flux counts the number of times a specific scintillation counter occurs in triggered events versus time. The vertical axis reports counts/minute/m2/steradian. The detector’s actual angular acceptance, in steradians, is not used, so the relative muon rate versus time is the real information contained in the plots. Blessing plots that measure how well the detector is functioning are also available. They provide the counters’ singles rates; hardware trigger rate and barometric pressure. Use of the Simple and Normal paths are the same. Have fun.


3. Muon Speed uses TimeOfFlight. TOF runs on only one file at a time and reports the time difference between each pair of counters. It also provides the ability to define a software trigger to study rates due to various combinations of counters. Converting that information to the muon’s speed (distance between counters/ time between counters) is complicated and constitutes the main difference between the two analysis paths mentioned above. The time of a signal arriving at the DAQ depends not only on the travel time between counters, but also on the counters' high voltage settings and signal cable lengths. The Normal analysis path forces you to use two runs with different configurations of counter positions to eliminate those other effects. In the Simple analysis path, all files have had the relative timing differences between counters calibrated away by adjusting their cable lengths in the Geometry file. This required separate data runs with counters placed next to each other and has been hidden from the user.


Take your choice. 


In the Simple path, TOF for each pair represents travel time for the muon between the counters. A plot of Time Difference versus separation for all pairs can be used to find the speed. Study speed versus time and combine results. Clean_TOF.pdf file list.


In the Normal path, two data sets must be compared to remove effects other than the travel time between counters. Plot TOF for a single pair of counters versus counter separation. Two entries suffice to extract the muon speed from the inverse slope. Clean_TOF_Normal.pdf file list.


4. A study of muon rates versus the Detector’s Angular Acceptance is also possible using TOF. The Simple path file listings provide the vertical positions of the counters. Combined with use of the software trigger logic in TOF, lets users measure rates for narrow versus wide angular acceptances defined by different combinations of counters. Use the number of entries in each TOF plot. Most detectors have 25cmx30cm active areas.


Let me know if you need assistance, or to share your creative ways to use the data. We can schedule a video meeting at your convenience.


5. Large Air Shower Array study - three detectors located on the 15th floor of the Fermilab High Rise collected data so students can explore the size and rate of cosmic ray air showers. This is the most complicated project presented in this link, however, students can study several aspects of air showers. Details are given in the attached PDF file CosmicRay_e-Lab_Large_Array.





Mark Adams

QuarkNet Cosmic Ray Coordinator

[email protected]