[b1_ana] LiD, Tensor Workshop Discussions, and Moving Forward

Sat Apr 12 15:27:55 EDT 2014

Hi Karl,

Thank you for the report. I may have had it in my files too, long ago.

In any case, one thing to keep in mind is that for the 1K bath temperature 
of the evaporation refrigerator we'll need to use in CEBAF's electron beam, 
the maximum LiD polarization at ~ 7.5 T is about 30%. The other points in 
Fig. 1 of the E159-161 CDR are at lower bath temperatures with dilution 
refrigerators.

What still needs to be confirmed is the ND3 polarization at high field, for 
which the results are inconclusive, due to possible inadequate microwave 
power, per UVA research run tech note. Table 1 on that note also is the 
source for the LiD point at 7.5 T in fig. 1 of the CDR you shared.

For using LiD and getting Pz  > 50% the question would be the cooling power 
of a, say, 0.4 T dilution fridge that could keep up with beam heating at low 
current. I mention 0.4 T because that's the upper number given in the E159 
CDR for the high LiD Pz seen at Saclay and Bonn. Since LiD's NMR is single 
peaked, there is no option of RF enhanced Pzz.

For example, in a 3 cm long target ionization heating at 50n A is about 350 
mW. Using some naive equations I found online, the cooling power to match 
this at 0.4 T would require a 3He circulation rate of  ~0.12 3He moles/s or 
about 0.35-0.4 g/s. I have no idea if this is a realistic number.

To decide whether LiD Pz > ~50% is feasible in beam, someone needs to:
1. simulate the beam power in the target with EGS4 or GEANT;
2. figure out whether dilution fridges at < ~0.5K can cool at ~ 300-400 mW;
3. compare the figure of merit for LiD at Pzz ~ 20% (Pz ~ 50%) vs ND3 at Pzz 
~ 30% (i.e. in beam mean Pz > ~ 50% +  4-5% pedestal RF-driven Pzz), 
including reduced overhead for LiD, better dilution factor, etc. The ND3 Pz 
here is based on improved polarization at B > ~ 6.5T.

If we are considering materials other then ND3, we need a fairly complete 
FOM optimization model to have a quantitative answer to our question of 
which material may be best, and what type of target would be needed to 
polarize it. This also assumes that the still pending question of ND3's 
Pz(B>5T) has been answered favorably.

Cheers,

Oscar

  Karl Slifer <karl.slifer at unh.edu> wrote:
> Hi
> 
> In advance of our meeting,
> here<https://www.slac.stanford.edu/exp/e161/target/cdrslacr3.pdf>is
> the conceptual design report for the E159 solenoidal target using LiD.
> I think this is a good reference to start with for considering some of the
> suggestions that emerged from the tensor workshop. In particular,
> 
> - Fig 1 gives LiD spin up times at 5T and 6.5T which is on the order of
> 30-40 hours. I think that with LiD, the polarization just keeps growing
> when you put beam on it, so data taking does not necessarily need to wait
> until max polarization is reached. T.E.s become a big time investment, and
> we would probably need to seriously consider AFP to kill the polarization,
> and maybe Josh's suggestion to simultaneously polarize the unused cell
> (which is just outside the uniform region) by use of an extra compensating
> coil.
> 
> -Max polarizations look to be about Pz=62% and Pz=72%, which corresponds 
>to
> about Pzz=30% and Pzz=40% respectively.  I assume this curve is for 1K, 
>but
> I can't access the original article (V. Bouffard et al J. Physique, 41,
> 1447 (1981)).
> 
> -the paper discusses using a transverse solenoid dipole for adiabatic 
>field
> reversals
> 
> -The proposed solenoid would have accomadated a 1cm diameter target, with
> 5cm length in a 10E-4 uniform field, with a 20 cm (8 inch) diameter bore.
> The price tag in 2001 was 230K. Inflation adjustment puts that at about
> $320K today.  The EIO tube ($95K) and Roots pumps(93K) in 2001 dollars
> inflates to about another $250K today.  These are not the only expenses,
> but they would be the main ones summing to 570K.  There's plenty of other
> smaller expenses, so maybe 800-900K for a complete solenoid system?
> 
> (For reference our UNH solenoid is 7T with 10E-4 uniformity over a 5 cm
> DSV, with a clear bore of 4 inches,and is about 14inches long.)
> 
> 
> -Karl
> 
> 
> 
> 
> 
> 
> On Fri, Apr 4, 2014 at 1:06 PM, Elena Long <ellie at jlab.org> wrote:
> 
>> Good afternoon,
>>
>> Thank you all for filling out the poll. Based on it, let's have our
>> next meeting on Thursday, April 17 at 2pm.
>>
>> The things that I would like to discuss are new rates calculations
>> using LiD and He2D (where Li is assumed to be HeD), I want to make sure
>> that we take the time close enough to the Tensor Workshop to hash out
>> any remaining discussions left over from the Workshop before they slip
>> from our minds, and to revisit our plan for achieving our condition
>> particularly given the pessimistic viewpoints that were raised during
>> the target session. I welcome any other agenda topics as well.
>>
>> Take care,
>> Ellie
>>
>> Elena Long, Ph.D.
>> Post Doctoral Research Associate
>> University of New Hampshire
>> elena.long at unh.edu
>> ellie at jlab.org
>> http://nuclear.unh.edu/~elong
>> (603) 862-5312
>>
>> On Fri 04 Apr 2014 11:57:55 AM EDT, Oscar Rondon-Aramayo wrote:
>> > Hi Ellie and all b1 people,
>> >
>> > I filled the poll, but I'm not sure about the reason for the meeting.
>> > Is there something time sensitive that we should discuss, such as
>> > communications with the PAC or the like? It would be a good idea to
>> > circulate a tentative agenda of the items that would be covered.
>> >
>> > Otherwise, it may be more effective to just share ideas and proposals
>> > by email, which also serves to document the process.
>> >
>> > Cheers,
>> >
>> > Oscar
>> >
>> > On Thu, 3 Apr 2014 17:14:10 -0400
>> >  Elena Long <ellie at jlab.org> wrote:
>> >> Good evening,
>> >>
>> >> Please take a moment to fill out the scheduling poll below by
>> >> tomorrow at 1pm so that we can schedule the next b1 meeting.
>> >>> http://doodle.com/4ytu2b3b5gqqaz7d
>> >>
>> >>
>> >> Take care,
>> >> Ellie
>> >>
>> >>
>> >>> On Apr 2, 2014, at 1:45 PM, "Elena Long" <ellie at jlab.org> wrote:
>> >>>
>> >>> Good afternoon,
>> >>>
>> >>> Since it looks like a number of people aren't able to make it next
>> >>> week, let's postpone to the following week. Since I imagine our
>> >>> schedules have changed a bit since our last meeting, please fill out
>> >>> the Doodle poll below by Friday afternoon so that we can schedule
>> >>> the next b1 meeting.
>> >>>
>> >>> http://doodle.com/4ytu2b3b5gqqaz7d
>> >>>
>> >>> Thank you,
>> >>> Ellie
>> >>>
>> >>> Elena Long, Ph.D.
>> >>> Post Doctoral Research Associate
>> >>> University of New Hampshire
>> >>> elena.long at unh.edu
>> >>> ellie at jlab.org
>> >>> http://nuclear.unh.edu/~elong
>> >>> (603) 862-5312
>> >>>
>> >>>> On 04/01/2014 11:07 AM, Long, Elena wrote:
>> >>>> Good morning,
>> >>>>
>> >>>> Since we last had a b1 meeting, a lot has happened. I was wondering 
>>if
>> >>>> we could schedule a meeting to re-group and plan a path forward,
>> >>>> particularly given the target discussions that happened during the
>> >>>> Tensor Workshop. Would next Thursday (4/10) at 1:30pm work for
>> >>>> everyone?
>> >>>>
>> >>>> Take care,
>> >>>> Ellie
>> >>>
>> >>> _______________________________________________
>> >>> b1_ana mailing list
>> >>> b1_ana at jlab.org
>> >>> https://mailman.jlab.org/mailman/listinfo/b1_ana
>> >>
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