ELOG ISOLDE

AIDA GELINA BRIKEN nToF CRIB ISOLDE CIRCE nTOFCapture DESPEC DTAS EDI_PSA 179Ta CARME StellarModelling DCF K40

ISOLDE

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Thu Sep 28 03:38:18 2017

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--original email text--
Using Claudia's code, I added a layer of Al foil before the heavy ion
silicon detector.  The attached plots correspond to the heavy ion
portion of fig 3(a) in the proposal.  Thus it only uses ground-state
transitions and doesn't account for geometry or efficiency etc.  I opt
to show only the highest and lowest beam energies for each simulation.

As I said before, something between 10 and 20 um of Al was likely to
be the correct choice, which is confirmed.  10 um is almost to thin to
guarantee the signals are below 200 MeV, while for 20 um we start
having issues of detecting the lowest energy recoils for the low
energy run.

We can discuss the selection in more detail at the next meeting, but
most probably we can just use some kitchen foil, adopting whatever its
thickness of 13 to 15 um depending what we find.

The attached file starts with no degrader, then adds 10 um Al, and 1
um Al steps up to 20 um.

--Updated 2 Oct to include 5 um ~ 10 um--

As ~185 MeV is the maximum energy, but the gain resistors may vary by up to ~10%, then the 'maximium safe energy' is about 160 MeV.  This we can get for the highest energy run 
with 15 um Al (we have it in stock); however, then the lowest energy case becomes about 30 MeV, or less than 1 MeV/u, which may be an issue for straggling etc.  So we will 
prepare two foils, as it is seen even for the low energy beam, it comes almost to 190 MeV without a degrader foil.  In fact, any foil thickness between 5 ~ 10 um may be okay 
(we have 8 um in stock).

Using also all 5 energies (212, 236, 260, 277, 295) then we see that the two lowest energies are okay for 8 um foil, and the three highest energies are suitable for 15 um foil.

NB: 19 Oct I deleted 15 um (previously attachment 2) and now it is attachment 8.

Note that the beam energy order (right to left, left to right) differs between the first PDF and the second two.

--4 Oct--
Existing 8um Al foils are not the right size.  Check 6 um and 10 um in detail, as we have more stock of these two.  Attached.

--12 Oct--

Attachments 5-7 show the 59Cu energy after the degrader foils for elastic (12C,12C) scattering.  Foil thicknesses are 6, 10, 15 um of Al, respectively.  Note that the angular 
range shows up to 15 degrees (larger than the case of the (p,a)).

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