Measurement of Eta (fiber trapping efficiency)

Compare with runs done by Alex and Hannah

First, a few important notes. When I went to make measurements on the sample, I realized that the sample was not in fact cemented together (as I had previously claimed). Instead, the samples halves and fiber were held in place with optical grease. Before making any measurements, I removed the fiber and cleaned both halves with methanol.

Also, the sample length is 4.5cm. Ryan, I want to make sure this is correct in your sim.

There is an off-centered machined hole on the rear face of the sample of the size of a SiPM. This may play a role in some weird behavior of optical photons.

I was unable to make a foil mask for the sample with a hole exactly the size of the fiber. The poked hole ended up being too large each time, which would allow light from the scintillator to leak through. Thus, I decided to try a new measurement configuration.

As the sample may have degraded over time, these results may not match the previous runs done by Alex.

Scint. rear: 3 layers of PTFE
Scint. outside: 3 layers of PTFE
Scint. face: coupled to PMT
Fiber: 4.5cm, flush with front and rear face of sample
PMT: coupled directly to the face of the sample with no mask

Scintillator sample

This is essentially a standard muon telescope run.

Data file: “20180625_JPB_1-72-1_1800V.dat”

Scint. rear: 3 layers of PTFE
Scint. outside: 3 layers of PTFE
Scint. front: bare
Fiber: 10cm, flush with rear face of sample, extended beyond front face of sample
PMT: poly cap with hole for fiber machined in it

Experimental setup
Poly cap for PMT	Foil covering poly cap
Sample with fiber sticking out	Sample with fiber sticking out coupled to PMT

For this run, the poly cap was attached to the PMT, coupled with optical grease. As the poly cap has 4 holes, a foil mask was placed over the poly cap and a hole was poked through the foil to only expose one hole.

The scintillator sample was clamped in place in the muon telescope, leaving the face exposed. The fiber was fed through the hole in the poly cap. It was ensured that the fiber was connected to the face of the PMT. Optical grease was present to couple the fiber and PMT.

Data file: “20180625_JPB_1-72-1_1800V_fiberOnly.dat”

Data
Scintillator + Fiber	Fiber Only

Here, the error is the width of the Gaussian fit.

Using these values, ETA was calculated to be 0.01816 (it was 0.207 for old data).
ETA_c was calculated to be 6.679 (it was 76 for old data).