Placed a hand held rad monitor near the faraday cup and took rate readings every 20 seconds, right after inserting the gate valve in front of SEC:

seconds counts/s

0    590
20    499
40    474
60    400
80    353
100    290
120    259
140    234
160    207
180    187
200    175
220    146
240    135
260    124
280    120
300    109
320    107
340    103
360    85
380    86
400    84
420    94
440    81
460    76
480    76
500    74

Then fitted this for half life.

Assuming a steady state background of 70 cps, and using the first 7 data points... the half life comes out as 82.1 +/-3.9 s.

Excellent agreement with known halflife of 59Cu.