out-of-context quotation JOY

"What we ACTUALLY need is a force field."
"Oh! Oh! What are you DOING, woman?"
--Tom "Tuda" Davinson

"Licking Beryllium is fine."
--Lothar

"Are you smelling my fruit?"
--Kelly

"What? That's not nice? ...I just don't understand people, do I?"
--Alex

"Of course there's a plan. As soon as I know what it is, I'll tell you."
--Pierre

"What we do is a bit of a mess."
--Alison

"I'm too chilled out to care."
--Simon

18O elastic scattering

31.5 MeV 18O beam corresponds to 1.75 MeV/u.

18Ne(a,p): rutherford backscattering from entrance foil

*Monitoring the backscattered beam in the upstream LEDA: What energies should we expect, and what resolutions? How much will LEDA be shielded by the entrance to the gas cell?
*Use 26.45 MeV beam (the new approved number for populating the 2.52 MeV resonance in the middle of the 2 cm cell); 4 cm diameter gas cell entrance 6 cm upstream of entrance foil; LEDA 20 cm upstream from the entrance.
*SRIMulations were used to set the energy losses of the beam through the foil
*plot the average energy in each strip against the average angle for each strip; error bars are the standard deviation of the energies.

Update on various simulations for 18Ne(a,p)

(Unless otherwise noted, all simulations below use 29.7 MeV 18Ne on 2 um Ni entrance window, 8 cm length of 150 torr He gas, baffle in place at 6 cm, Ni exit window (default 6 um), 1000 um LEDA at 20 cm downstream, S2 immediately behind LEDA.)

1. Consider effect of different thicknesses of exit window: 6 um Ni vs 2 um Ni; also degraders in front of S2.
Here is the energy-vs-angle plot for energy deposited in the detectors (*includes* dead layer effects; also includes a 50 um Al degrader foil in front of the S2 only).



Here is a plot of the energy spectrum in Strip #7 of the LEDA, for both exit window thicknesses. The energy resolution changes only very slightly.


Effective thickness of the detectors--oops, still assuming LEDA is 500 um instead of 1000 um, so ignore the larger groups on this plot. The smaller groups are the particles that hit the S2. Their energies are still high enough and their angles low enough that they can punch through the detector--this is with the 50 um Al degrader in place.


to do: check effect of 6 um Ni degrader in front of S2.

2. Elastic scattering of protons from contaminants on exit window (assume entrance window is blocked by baffle). The protons are on the inside surface of the 2 um exit window: the beam stops in the window, so there is no scattering from the outside surface.
(sorry for the low stats) (I also tried running a 6 um exit window, but I think the protons must all stop in the window--to do: double check this with Srim range tables.)

3. Beam elastic scattering on Ni entrance window. (It was suggested to use a gold foil in front of the entrance window, but Kelly checked the relevant energy losses and they would push the resonance out of the active area of the cell.) --in progress!