Cf252 runs with HPGe

Detector efficiency measurements using a Cf-252 source.

Cf-252 source description

Serial Number: FTC-CFZ-431

Mass:On 03/19/1993 the Cf-252 mass was 4.2[math]\mu g[/math]. ( [math]1\mu g[/math] is expected to emit [math]2.3 \times 10^6 n/s[/math])

Half Life= 2.652 years

Neutron fluence:On 03/19/1993 the Cf-252 the neutron rate was [math]10^{7} n/s[/math]. Base on the mass one would expect [math]4 \times (2.3 \times 10^6 n/s) = 9.2 \times 10^7 n/s[/math].

Neutron energy spectrum (from A.B.Smith et.al, Physics. Rev. Vol 108 #2 pg 411-414, 1957 File:PhysRev108p411957.pdf):

Decay: Cf-252 undergoes alpha decay to Curium (cm-248) 96.9% of the time. The rest of the time it will undergo spontaneous Fission emitting 3.7 neutrons on average per fission.

The Fission Fragment Yield as a function Fission fragment Atomic Number ([math]Z[/math]) and Atomic Mass Number ([math]A[/math]) from Wahl, A., At. Data and Nuc. Data Tab., vol. 39, (1988) .

HpGe Neutron Damage

I made a page discussing neutron damage to the HPGe detector (Fast_neutron_damage_to_HPGe_Detector) as a function of the total amount of fast neutrons per [math]cm^2[/math] irradiated on the detector face. [math]5 \times 10^6 n/cm^2[/math] is a factor of 10 below the point where damage was first observed in an experiment.

RunPlan

Object: Determine if an HpGe detector can be using to tag neutrons and identify the isotope species parent of the neutron

Runlist

12/29/16

No poly was used to shield the HPGe detector.

Run #	RunTime [sec]	distance[cm]	n flux [math][\frac{n}{cm^2}][/math] [math]=\frac{n_{rate}t}{4\pi d^2}[/math] (Cf252 rates)	Integral n flux [math][\frac{n}{cm^2}] [/math]	configuration	notes
5609	4060	30	6850	6850	Cf252 in. Coincidence between HPGe and timing PMT	A ToF spectrum exists but is very hectic. Problem may be that the TDC stop is determined by a widened timing PMT pulse in coinc. with a HPGe pulse that has high timing jitter.
none	1250	26	2800	9655	Not taking data during this time.
5611	2509	30	4230	13885	Cf252 in. Coincidence between HPGe and timing PMT. TDC stop was changed to always be 1200 ns after PMT timing pulse, otherwise same setup as 5609.	ToF looks good. Neutron rate approx. 3 Hz for detector 90.
5613	10025	15	0	13885	Na-22 source. Coincidence between HPGe and timing PMT	Calibration
5614	654	15	0	13885	Co-60 source. Coincidence between HPGe and timing PMT	Calibration

go back Total n flux: 13885 n/cm^2