[Isotope-prod] Comments on Ga activation rates

[George Kharashvili]

Yes, 4 hr irradiation with 40 MeV, 50 kW beam (1-1.5 mm W radiator, 210 g Ga sample) would produce approximately 40 mCi of Cu-67 (results pending experimental validation). About 1/4 of it will decay in 24 h leaving us to work with ~30 mCi.

--
George Kharashvili
Jefferson Lab Radiation Control
757-269-6435

----- Original Message -----
From: "Hari Areti" <areti at jlab.org>
To: "George Kharashvili" <georgek at jlab.org>
Cc: isotope-prod at jlab.org
Sent: Monday, January 11, 2016 4:21:03 PM
Subject: Re: [Isotope-prod] Comments on Ga activation rates

Dear George, 
If I understand correctly, Tables 3.1 and 3.2 use infinitely large radiation length 
gallium targets. The numbers below are production rates for finite RL target, not 
the activity after 1 day after irradiation. 
For reasons of overhead, i.e. 4 hrs. of set up, it appears that the irradiation should 
be for 4 hrs. In this case, for the 210 gm target, we can expect 40 mCi production 
and a day after that, somewhat lower activity. Is that right? Longer irradiation time 
has the advantage that the cost/mCI is lower. Thanks. 
-H 



From: "George Kharashvili" <georgek at jlab.org> 
To: isotope-prod at jlab.org 
Sent: Friday, January 8, 2016 5:10:40 PM 
Subject: [Isotope-prod] Comments on Ga activation rates 

Dear collaboration members, 

I did some modeling to include activation rates of various targets mentioned yesterday. Here are some conclusions: 
- There is no good reason to increase radiator thickness - 1 to 1.5 mm tungsten is optimal. 
- Activation rates presented in the proposal (17 mCi/h/kW at 40 MeV) were calculated for what can be assumed an infinite natural Ga target. Replacing it with other targets results in the following: 
3cm diameter, 5 cm long cylinder (m=210g) - 10 mCi/h/50kW 
3cm diameter, 10 cm long cylinder (m=420g) - 12 mCi/h/50kW 
Truncated cone D1=1.5cm D2=10.6cm H=6.5cm (m=1310g) (currently in the proposal) - 13 mCi/h/50kW 
Truncated cone D1=2cm D2=6cm H=10cm (m=800g) - 12 mCi/h/50kW 
Truncated cone D1=1.5cm D2=15.5cm H=10cm (m=4110g) - 15 mCi/h/50kW 

If we take the smallest of these targets (~200g) and assume 20 hours of 50 kW beam (ignoring decay of Cu-67), we should produce ~200 mCi of Cu-67. This is roughly 260 nanograms, or 1.3 ppb of Cu-67 in our 200 g natural Ga target, which is greater than the 0.5 ppb of Cu content of 99.9999% Ga sample. 

I hope this information is useful for the proposal. 

-- 
George Kharashvili 
Jefferson Lab Radiation Control 
757-269-6435 
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