[Isotope-prod] Comments on Ga activation rates

[Pavel Degtiarenko]

Dear All,

If the value of the specific activity is the most critical parameter, we 
could adjust other parameters and bring them to their limits to maximize 
the specific activity. For example, the dependence on the beam size is 
almost quadratic. Decreasing the beam spread (and the target) diameter 
by a factor 2 would increase the SA by a factor about 4. If the power 
density in the Tungsten entrance window gets too high, we could decrease 
the beam current, balancing it with increasing irradiation time. Other 
parameters will play, too.

I believe we may say that our current numbers should be considered as 
preliminary, subject to the future multi-parameter cost optimization 
process. That would require initial measurements and tests (cross 
sections at several energies, Cu-67 extraction parameters, etc.)

Best regards,
Pavel

On 1/9/2016 11:04 AM, George Neil wrote:
> George
> I think this is great and I like the idea of the small mass 
> (especially if we are starting with the ultrapure target).
> My only question is: what is the potential market for this isotope?   
> There is no point in making 200 mCi if you can only sell 10 mCi at a 
> given point in time.   I thought I had asked this question before and 
> gotten an answer around 10 mCi but maybe I didn't state it clearly.
> If you had 200 mCi to sell would there be enough buyers?
> George
>
>
> On 1/8/2016 5:10 PM, George Kharashvili wrote:
>> 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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