PREX/CREX Feb 2 2017 1:00pm EDT

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Logistic information

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 Room IRL:                            CEBAF F227

Agenda

1. CREX Contamination: Seamus [Old Post] [More info] [also here]
   • SR: new slides show the equations used to calculate the asymmetry
   • SR: assume all asymmetry for contaminants (all symmetric and light — Ca48 O16) can be pinpointed to within few percent. BM: how do we know what is in there? SR: we trust the assay and then make some reasonable assumption about the contamination. The assay is in haplog 3111 says that Ca40 is 10%. KP: this was attached to the shipment of the Ca48 target. SR: there are still some questions related to a different assay that RadCon was working from. NEEDS To be tracked down (after ERR should be fine).
   • KP: how about Ca44? SR: you can treat those as perturbations on the other Ca isotopes. KK: may be useful to talk to Chuck and make sure that these won’t have any properties that are adverse to the experiment. SR: from discussion we already had (in general) Chuck said those are benign. BM: low lying states tend to be isoscalers
   • SR: i think we should scape because there may be heavier stuff in the oxidation. if we sweep away as much as possible of the contamination is worth doing.
   • SR: assumptions on what the values for the contaminants are and the asymmetries for each. (these are educated guesses).
   • SR: the conservative estimate is that it’s between 1.3 to 2 ppm. we NEED calculations for this like with Ca48 (after ERR). KK: i think 1.3 is too conservative, it is double counting the distortions. you should do the skinless argument and then be done. SR: probably right but just wanted to be conservative. KK: where is Ca40 first excited state? SR: there is a paper that has those. but that is a factor 10 suppressed compared to 48.
   • KP: 1% may not be that easy … 50um layer. BM: talking about the chemistry. do we really know what happens? how deep they go and what is left after we scrape? KP: we need to accumulate that information.
   • SR: second to last slide: negligent in FF. if we have 8% oxidation, with FF it’s 4% of the signal and if we consider the asymmetry is 2ppm it will be within the noise of what we propose.
   • KK: we should present it as how thick of a layer we would have and then get an uncertainty on that.
   • SR: we need to redo the calculation for CREX5. The FF may work against us. We need tables from Chuck for all of these and run it through MC for acceptance. Will get it done before ERR.

Attendance

Ciprian G, Seamus R, Kent P, Tyler K, Caryn P, Bob M, Guido U, KK, Paul S, Dustin M