🚀 go-pugleaf

WHAT FOLLOWS IN SMALL PRINT IS A MESSAGE POSTED LAST NIGHT ON THE PHYS-L
SERVER. I VERIFIED THE REPORT (BY MARK SYLVESTER, A TEACHER FROM TRIEST)
THAT MONITOR SCREENS ARE SLIGHTLY RADIOACTIVE. A NICE TOPIC FOR STUDENT
RESEARCH (INVESTIGATING THEIR HOME TV SCREENS), IF YOU HAVE A DETECTOR
IN SCHOOL.

ARE YOU READY FOR THE CELEBRATION OF THE 100th ANIVERSARY OF THE DISCOVERY
OF RADIOACTIVITY IN 1997? PENETRATING RADIATIONS FROM URANIUM WERE
DISCOVERED IN PARIS ONE YEAR AFTER THE DISCOVERY OF X RAYS BY ROENTGEN.
IT TOOK SEVERAL DECADES TO UNDERSTAND THEM. MARIE CURIE AND ERNEST
RUTHERFORD WERE MAJOR PLAYERS. WHAT DO YOU DO TO FAMILIARIZE STUDENTS
WITH BIOGRAPHIES OF THESE TWO SCIENTISTS?

                       **********************

According to today's message from Mark Sylvester (msylvester@gn.apc.org)
the monitor screens have a tendency to concentrate ambiant radioactivity
(presumably from radon). I would like to confirm his observation; the
radioacticity I measured was about twice as large as the background.

A small piece of wet paper towel (about 2*2 cm) was used to wipe the
screens of three working computer monitors, one after another. It was
then placed directly in front of a GM tube. The count was 316 in 5 min;
the background count for that time was 162. Two hours later the
measurements were repeated several times; the countings were essentially
unchanged. The window of my GM tube is thin enough to count alpha particles
from an Am-241 source situated 1 cm away; it was too thick to count them
from the distance of 2 cm (in air). Not all counts are due to alpha
particles, as verified by placing up to 20 absorbers (0.9 mg/cm^2 each)
between the wiping paper and the GM tube.

Your discovery, Mark, can be turned to a nice activity for students. For
example, study the effect of ventilation on the accumulated radioactivity.

       Ludwik Kowalski           Kowalski@apollo.montclair.edu