Mathematical and Physical Journal
for High Schools
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# Problem P. 4202. (November 2009)

P. 4202. A Geiger--Müller tube (GM tube) is used to detect radiation, which is emitted by a pointlike high-energy source, during 1 minute. The table below shows the distance between the source and the window of the GM tube, r, and the averages of the detected number of strikes, N, (decreased with the backround radiation).

 r [cm] 1 3 6 9 N [1/min] 487 196 72 41

Estimate the number of strikes per minute when the source is placed at a distance of 12 cm from the window of the GM tube.

Hint: The length of a GM tube is between several cm-s and some dm-s. There are strikes in the whole length of the tube, but the process can be modelled such that the strikes are at a sensitive surface at some distance from the window. The source is usually placed perpendicularly to the window in the symmetry axis of the GM tube.

(5 pont)

Deadline expired on December 10, 2009.

Sorry, the solution is available only in Hungarian. Google translation

Megoldás. Kb. $\displaystyle 26-28$ beütés várható percenként 12 cm-es távolságnál.

### Statistics:

 25 students sent a solution. 5 points: Bolgár Dániel, Farkas Martin, Galzó Ákos Ferenc, Hartstein Máté, Lájer Márton, Pálovics Péter, Patartics Bálint, Sápi András, Szabó 928 Attila, Tamás Zsolt, Timkó Réka, Varju 105 Tamás, Vécsey Máté. 4 points: Jéhn Zoltán, Szélig Áron. 2 points: 1 student. 1 point: 9 students.

Problems in Physics of KöMaL, November 2009