Half life Results- Protactinium-234 and Indium-116

Here are the results from the Protactinium Generator Experiment. Your task is to correct for background (take the background count per second away from the count rate) and then plot a graph of count rate (cps) against time (s). Remember the count rate was taken every 10 s but shows the value of the count rate (for one second)

Background count rate (c.p.m.) 48.0,   46.0,   42.0

Average background count rate (c.p.m.)    45.3

Average background per second (c.p.s.)    work it out!

Time	Count rate
(s)	(cps)
0	80.3
10	73.9
20	67.3
30	60.5
40	55.2
50	49.6
60	45.7
70	41.5
80	37.4
90	34.1
100	31.3
110	28.5
120	25.9
130	23.9
140	21.7
150	19.4
160	17.6
170	16
180	14.9
190	13.4
200	12.3
210	11.2
220	10.2
230	9.2
240	8.4
250	7.5
260	6.9
270	6.4
280	5.7
290	5.3
300	4.7

Indium 116 Half Life

Here are the results for the Indium-116 half life experiment. Warning, do not plot a graph in 15 minute intervals or you will have more difficulty finding the half life. Make the scale ten minute intervals.

You can track the experiment yourself through the link below

Indium-116 files

Background count = 31 c.p.m.

Time	Time from start	Count rate
(hours)	(mins)	(c.p.s.)
9:00	0	675
9:15	15	570
9:30	30	452
9:45	45	375
10:00	60	328
10:15	75	275
10:30	90	219
10:45	105	181
11:00	120	164
11:15	135	149
11:30	150	126
11:45	165	106
12:00	180	90

 

Here are three more examples for you to practice producing a half life graph and for finding the half life of Protactinium

Example 1:

Background Count (cps):    5,   5,   3,  5,   4,   5,   5.

Time (s)	Count in 10s
0	308
10	279
20	240
30	217
40	197
50	182
60	165
70	158
80	145
90	129
100	116
110	109
120	98
130	89
140	80
150	75
160	66
170	60
180	55
190	50
200	46
210	43
220	35

Example 2:

Background Count (cps):     4,       3,      5.

Time (s)	Count in 10s
0	841
10	752
20	693
30	622
40	593
50	544
60	481
70	443
80	392
90	364
100	341
110	301
120	272
130	251
140	243
150	211
160	204
170	183
180	172

Example 3:

time (s)	Count in 10s	corrected count in 10s	Corrected Count Rate (cps)	Background count (cp10s)
0
5	105	100.5	10.05	5
20	95	90.5	9.05	5
35	81	76.5	7.65	3
50	90	85.5	8.55	5
65	86	81.5	8.15	4.5
80	73	68.5	6.85
95	76	71.5	7.15
110	79	74.5	7.45
125	53	48.5	4.85
140	53	48.5	4.85
155	58	53.5	5.35
170	61	56.5	5.65
185	60	55.5	5.55
200	43	38.5	3.85
215	60	55.5	5.55
230	48	43.5	4.35
245	45	40.5	4.05
260	44	39.5	3.95
275	42	37.5	3.75
290	47	42.5	4.25
305	28	23.5	2.35
320	31	26.5	2.65
335	36	31.5	3.15
350	32	27.5	2.75
365	24	19.5	1.95

You should now have had plenty of practice at finding the half life graphically, nothing should phase you now.

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