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Looking for Stopping Cosmics

Why? Well stopping cosmics is the only thing that can be used as a standard candle between the 3 minos detectors. We can use them to inter-calibrate the detectors. Eventually we'll be interested in the dE/dX spectrum (which should look kinda like this) but to start with it's hard enough just finding them!

A lot of cosmics look like this. They just go straight through the detector in all 4 views. This is no good.

Some cosmics look like this. You've got to look at all 4 views separately and try and build up a picture in your mind of what the hells going on. For all these plots, the first one on the left is green with horizontal strips, then green with vertical strips followed by clear horizontal and clear vertical. In the two vertical views this muon only hits a few planes. This is more than likely a muon that has come into the top of the detector at a very steep angle (top to bottom) and has only hit a few planes before leaving. This muon definitely hasn't stopped. In the other view you can also see that the muon hasn't stopped because it's hit strip 1 AND strip 23 so it's just gone straight through the detector.

So it would be cool if you could try to write an algorithm that looks for these stopping cosmics. I have a list of stoppers that I did by eye (!) so you can compare your algorithm's selection to it. It would also be a good idea to have a look through some of them just to see what they look like.

So you're probably thinking 'piece of cake! I just look at strip 0 and strip 23 for hits to see if stuff has come in the sides and top of the detector and I guess plane 0 and plane 59 to see if things have come in through the front and back.'
But sometimes stuff that comes in at a really steep angle doesn't hit any strips until quite late (strip 20 in this case in view 3) So you could say 'well then, I look for stuff hitting strips 0-3, 20-23 and planes 0-3 and 56-59.' Trouble is you might find yourself missing a load of stopping muons that are coming in close to the edge of the detector.

Look at this bastrad. View 3. I don't think it's possible to tell for certain if this stopped or not. To begin with it looks like it probably stopped around strip 8. But you can see that it starts to curve as it enters the detector. In fact it's quite likely that this muon has just gone BETWEEN the planes and left the detector around plane 12, strip 0. For the time being you should probably keep all the ones that look like this (flag them if possible) and decide what to do with them later.

This one's a bit of a biatch... It could have stopped, I guess...? I usually assume these ones have gone out the side of the detector.

This is a bona fide stopping muon. It comes in the front of the detector and stops a little way in. There's no way it curved out of the detector or anything. In fact this isn't a cosmic muon; it's a muon created somewhere in CERN that happens to have hit our detector. But for the time being we want to keep all these too because we can probably use them. So the vast majority of stoppers will look something like this, coming in the front or the left side of the detector. But what we REALLY want is genuine stopping cosmics that come in the side or top or back of the detector and stop somewhere in the middle. You may not actually find any of these but your algorithm has to BE ABLE to find them. Don't go looking for stuff that only comes in the front of the detector. You may find all these artificial 'PS-like' muons but you won't get any of the real cosmics. I say PS-like because this muon has a low energy (otherwise it wouldn't have stopped!). Real PS muons tend be around 25 GeV and so do this in our detector. Notice that they also tend to be right in the middle of the detector in at least 2 views.

Watch out for ones like this. So I think that a cosmic has to be either going forwards or backwards through the detector, regardless of what angle they are coming in at. So at first glance, this looks like it could be a stopping muon. But look at what plane they stop at in the 4 separate views. In the first plot, it looks like the muon is coming into the detector around plane 30 and stopping around plane 20. But in the second view it looks like the muon is coming in around plane 20 and stopping at plane 30. This obviously can't be true. This is also NOT a stopping muon.

So my existing code is in: pcminos01:/home/lj/loonleo/latestFeb2003/
You want 'lookforstoppingcosmics.C', 'lookforstoppingcosmics.h' and 'Tracker60013_cosmic.root'
This will display the cosmics like the event display you wrote yourself for the beam muons already. There's also some basic algorithm there to look for stoppers but frankly it's shat. It would be better if you started from scratch yourself. But you can use my code as a skeleton if you like.
There's also a 3D event display but it's a bit rubbish. I wouldn't rely on it too much.
There's also a plot of timing information. Early hits are blue and later hits are red. So you might think 'Wicked! I can use the timing info to sort out exactly whats going on!' Unfortunately the timing stuff at CalDet is not calibrated so this info cannot be used reliably. Still, you may want to have a look at it.
There's some extra info from Chris' Tracker that you may find useful i.e. the angle the muon went through the detector and a calculated 'what strip would the muon hit in plane 0 if you extend the track back there'. I've put comments in the code to show you where they are and what they're called.

Good luck!

Got one! I think this is a genuine stopping cosmic. It looks quite a bit like a PS muon but it's coming in from the right and I don't see many there.