4. A Sensitive Situation
In order to study a cosmic phenomenon, there are several factors to
consider when designing your detector system. One is how bright the
phenomena are that you will be studying. Related to this is how often
an event of a given brightness occurs. If you dont understand
these things, you could look for a very long time and see nothing...or
you could be blown away by the first event!
Examine the plot below. Note that it is a Log-Log plot, so think
carefully in trying to answer the questions below. On the X-axis you
see the number of photons per square centimeter per sec detected from
a GRB (this is merely a measure of its brightness) and on the Y-axis
you see the number of bursts each year which are that bright or
brighter. These bursts can occur anywhere in the sky. So we will
assume that our detector is located far from Earth and can
continuously view the entire celestial sphere.
1.) If your detector can measure bursts which are 100 photons per cm2
per sec or brighter, how many GRBs would you detect each year?
2.) If you are designing a new detector and want to be able to detect
about two GRBs per week, what are the dimmest bursts that you would detect?
What does this mean about how sensitive a detector you must design?
3.) If your detector is 100 times more sensitive than what you found
in (1), how many GRBs would you detect each week?
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