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On inverse gravitational lensing, Im not sure exactly what you mean
originally posted by: ErosA433
a reply to: ChaoticOrder
Thanks for the link, i gave it a read and it would appear to now make sense, though it sort of requires or stipulates that the negative mass exists in a shell like halo around each galaxy and between them.
Interesting concept though, was a good read and is, probably more plausible than the EU models.
this way, any ionization produced inside the volume will drift in the electric field, toward the top mesh.....if you know the field strength of your field cage, then the drift velocity is roughly constant
you recieve primary signal during the actual event, when the Xenon is ionized by some source and the Xenon scintillates, producing light. When the charge is extracted from the liquid, into the gas space, it produces another signal, a secondary signal.
thus you can figure out exactly where in the detector the event happened.
You can use this signal to figure out things like... the type of event it is, how much energy was contained in the event... etc.
In vacuum any ionization would continually accelerate in a constant electric field, so does the dE/dx force from passing through the Xenon result so the "drift velocity is roughly constant"? (I could work out dE/dx, but I suspect you already know the answer for me, and that would add clarity for me and perhaps others.)
At first it occurred to me that if the Xenon scintillates because of the ionization, and the ionization flows upward because of the electric field, that you'd get a continuous stream of primary events, not just a single primary event. But after thinking about it, I am guessing it only scintillates during the initial ionization. That would mean to me that as the ionization drifts upward it never gets enough energy to further ionize other Xenon along the way - do I have that right? Or does each event involve several scinitillations? Also, I would expect the scintillations to go in any direction at all, so I believe it must have PMTs in all four pi steradians of coverage - right? It might be helpful also if you could mention what the cause is for the second light signal as it goes through the gas (I'm guessing the pressure is just right so that enough acceleration now occurs due to the lower dE/dx that you get a second ionization?).
I can see how you can figure out where longitudinally the event occurs (reasonably exactly, never exactly exactly of course) but I don't see how you can determine the transverse position, if you only get a single photon for each event that might go off at any angle. I'm also thinking the timing of the photon travel is negligible, and that the ionization is all moving at non-relativistic speeds. Is that right?
It would be helpful to mention how all that can be figured out.
And what is a Q-ball?
Also, what is the theory on how the ionization occurs in the first place? I am guessing they are looking for a random WIMP to pass through the Xenon, and that somehow produces ionization. But what is the theory that makes Xenon a good fit for a 50 GeV WIMP? Is this reasonably simple to describe? Or does it involve the full glory and complexity of the standard model Lagrangian to make the predictions? Since the matter is "dark" I'd expect it not to interact much at all with normal matter in the first place. While they are proposed to interact gravitationally, any gravitational effects would be immensely weak for single particle events, so I can't imagine its gravity. Perhaps you can shed some light on how things are expected to produce the ionization?
And then there is the issue of background. I would expect that there would be significant cosmic ray background. I am guessing a WIMP signature would differ from signatures of other sources of ionization?
Well thanks again, as this is interesting. And if you get a chance, I hope you can watch and comment on the video I produced (my most recent ATS thread) as I always appreciate your feedback. At 31 minutes, I am afraid the video is a tad long, so I don't think many have watched it. It went over extremely well at Brookhaven National Lab, and my colleague said I should put together a 2-3 minute summary, since if well done it might generate enough interest for people to spend the 31 minutes. 2-3 minutes will be tough of course, but I'm thinking about how to do it. The problem is that you can't replace the standard model with a tweet!