Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 1 Radioactivity HW 7 How can the element 106 (seaborgium) in general be produced? What makes 14 C famous? What is the medical importance of 18 F? Comment on 152 Dy. How can its gamma decay be measured?

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 2 Radioactivity ≡ decay constant. It does not change with time, and does not depend (to a good approximation) on any environmental factors. (It does in extreme cosmic conditions. How?). Compare to human life time!!! HW 8

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 3 Show that the mean lifetime. N is difficult to measure. Instead, measure  N ≡ number of decays between t and t +  t :  t <<  (i.e. << t 1/2 ) If  t <<  (i.e. << t 1/2 ) then show that and thus defining the activity A(t ): RadioactivitySlope=?!!!!!!!!!! Be careful. Krane Ch 6 HW 9

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 4 Radioactivity HW 10 Krane Problem 6.1

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 5 Radioactivity Activity measured in units of becquerel (Bq) = 1 decay/s. 1 curie (Ci) = 3.7 x Bq. Activity is not dose!!!!! Isotope 1 (initial number N 0 ) decays into “stable” isotope 2: In order to measure using the exponential decay curve:  The half-life should be not too long; we need to see the sample decaying!!! Actually we can use provided this information is available.  The half-life should be not too short; we need to do a series of measurements!! But there are other alternatives!!  1 should not be produced, 2 should not be radioactive. Krane 7.8

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 6 Radioactivity Exponential decay of species 1 and exponential growth of species 2.

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 7 Radioactivity

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 8 Radioactivity 847 keV 1811 keV 56 Mn In order to measure t 1/2 when it is not too long and not too short compared to practical experimental time, use the exponential decay curve. Are they in cascade? Coincidence summing!! Which line to measure?

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 9 If t 1/2 is too long, How can we measure N? If t 1/2 is too short, multiscaling or coincidences or Doppler or..! Multiscaling Multiscaling, dwell time, accept logic pulses, register number of logic pulses during dwell time in successive channels  decay curve. If t 1/2 is less than 1 ms, need high activity, detector and electronics maximum count rate!! say 10 5 /s, dwell time 1 ms, maximum counts per channel = 100  bad statistics!! Coincidences….. Doppler……. Doppler……. Radioactivity HW 11 Specific activity. Project 3

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 10 RadioactivityTAC TAC

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 11 Radioactivity If parent nucleus decays by two modes: Derive.

Radiation Detection and Measurement, JU, First Semester, (Saed Dababneh). 12 Radioactivity two If we measure gross activity for a sample containing two isotopes. Better, and if possible, measure each isotope separately using its signatures with suitable spectroscopic techniques. We will encounter such techniques later in this course.