Talk:DAMA/NaI
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[edit] Model-dependent
Nice article! The comment about DAMA's results being "100% model-independent," in contrast to other experiments, is not really accurate. It is model-independent that DAMA sees an annual modulation, but connecting this to a detection of WIMPs is no less model-dependent than it is for other experiments. The comparison of different experiments with different detection techniques or detector materials, is almost unavoidable model-dependent at some level. Reuben 02:02, 24 Nov 2004 (UTC)
Yes, I agree that 100% model independent is a too strong a statement! What is true, however, is that most other experiments, e.g. the CDMS experiment, have to make more assumptions about what a WIMP recoil will look like in their experiments. All that DAMA does in this respect is reject multiple scattering events. They don't even separate electron recoils from nuclear recoils (WIMPs are assumed to only cause nuclear recoils)!
The other experiments don't have enough statistics to see an annual modulation. They could have seen a few WIMP events at most (none have been seen so far). So, they have to actively reject background events. Electron recoils are easily separated from nuclear recoils. But nuclear recoils can be caused by neutrons and WIMPs. They use a variety of strategies to account for the contribution of neutrons and then they see if there is a statistically significant excess of events.
62.238.255.224 16:13, 26 Nov 2004 (UTC)
I've deleted the sentence about 100% model independence. It would be a bit too much to replace that comment with what I really meant (the above comments). This point is also made in Ref. [1] by R. Bernabei et al.
62.238.255.223 18:55, 26 Nov 2004 (UTC)
- Without going into all the gory details, suffice it to say that the arguments on this subject presented by Bernabei et al. are not a neutral point of view. I believe it would be fine to say that comparisons between different detection technologies have some degree of model dependence. Reuben 05:50, 30 Nov 2004 (UTC)
- Yes, I agree. Also, there is an article by Kamionkowski about another possible way to account for the DAMA signal. That's also worth mentioning
Count Iblis 16:09, 30 Nov 2004 (UTC)
[edit] New DAMA paper
I haven't read it yet, but it's on the arxiv: [1] -- Reuben 18:15, 28 Jan 2005 (UTC)
Interesting, thanks!
Count Iblis 13:46, 29 Jan 2005 (UTC)
[edit] Error?
"All these other searches use sophisticated background elimination techniques instead of the annual modulation technique." Surely all the searches are also looking for time varying dark matter flux in addition to background vetonig...
Well, all the other searches have insufficent statistics to use the annual modulation technique. E.g. the CDMSII experiment could only have detected a few WIMP recoil events during their measuring period. Now they did detect some events, but they concluded that they were due to neutrons. Note that the amplitude of the annual modulation is expected to be only about 7% of the total WIMP detection rate.
Unlike experiments such as CDMSII wich use crystals of a few hundred grams, DAMA/NAi uses ten crystals of 10 kg each and unlike the other experiments which have collected data for a few months, DAMA/NaI has collected data for 7 years. So their total exposure in kilogram days is enormously larger than any other experiment. This allows them to do statistical analyses using the annual modulation technique.
Count Iblis 14:59, 4 Feb 2005 (UTC)
