The QuarkNet Online Cosmic Ray Detector

 		  
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Accessing and Understanding the Data
The image to the left shows 30 lines of raw data recorded in July of 2002. We have highlighted two different "events" or instances in which the detector recorded observations.

Line #2 is the most common event in the detector. The data indicate that a cosmic ray passed through two of the detector's counters and continued on through. The first column indicates the amount of elapsed time since the last observed cosmic ray and the second column provides information about which counters observed the cosmic ray.

Line #27 indicates a more rare event; a cosmic ray that entered the detector and did not have enough energy to make it out. The other two columns of information indicate that the particle was at rest in the detector for a period of time and then decayed into other particles. The third column indicates which counter observed this decay. The fourth column indicates the amount of time between the cosmic ray entering the detector and its decay.

We'll call events like #2 a trigger and events like #27 a candidate. The word choice is very careful. We may be tempted to call these cosmic rays and decays. Can you think of a reason to withold that judgment until later? How many triggers are in these data? How many candidates?

You have probably noticed that these raw data contain letters and numbers. These are all hexadecimal (base 16) numbers. Each digit ranges from 0-9 and A-F in order, so hexadecimal counting would go like 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F. While these numbers are "hex," data posted on this website have been "cleaned up" and look like the image to the right. You won't need to convert from hex to decimal.

The data are recorded in 24 hour blocks; each day starts at noon Greenwich Time. The name of a data file corresponds to the Julian Day Number for that date, the Julian Calendar uses integers to define dates. 31 July 2002 is 2452487 in the Julian Calendar. The sequential nature of the dates makes working with the data easier.

Data tutorial - Provides more details for data analysis.
Summary Data - Reports the number of triggers and candidates observed during that run. The file also reports the amount of time elapsed during the run. The time may be less than 24 hours as data collection is sometimes interrupted for detector adjustments.
Trigger Data - Reports out the trigger information observed during that run.
Candidate Data - Reports out the events that may be cosmic ray decays.
All events - The original data file (converted from hex to decimal).
Julian Day Number Calculator - Use this to convert the day number in your file names to a "real date."
Still in development Live Data - A new window with a copy of the current, raw data file as it grows. The window periodically auto-refreshes.

Project Contact: Thomas Jordan - jordant@fnal.gov
Web Maintainer: qnet-webmaster@fnal.gov

Last Updated: 31 July 2002