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Neutrino Oscillations in Venice April 16, 2008

Posted by dorigo in news, personal, physics, science, travel.

I spent the afternoon today at a conference on neutrino physics, . The conference is held this week in my beloved home town, and precisely in Palazzo Franchetti, which houses the Istituto Veneto di Scienze, Lettere e Arti, a pleasant venue close to the Grand Canal.

The program of the day was centered on astrophysics, and I decided to visit the conference to find inspiration for two forthcoming talks I will be giving, one in Padova next week and one in Albuquerque next month. The nice weather made for a pleasant coffee break: below you can see a pic of mself in palazzo Franchetti’s garden.

Later today – if I have enough stamina – I will post my summary of a couple of interesting talks:

  • G. Steigman, Neutrinos and Big Bang Nucleosynthesis
  • G.F. Giudice, Colliders and Cosmology

For now, I can only say that I did learn from the above talks some interesting details on the information about relic neutrinos one can extract from big-bang nucleosynthesis, and on the complementarity of searches for dark matter in direct astrophysics experiments and at the Large Hadron Collider…

UPDATE: I found out yesterday evening that Alexey Petrov is also at this conference, and in fact he discusses in his blog the talk given yesterday by R.Bernabei about the tentative dark matter signal observed by DAMA-LIBRA.

UPDATE 2: since this post is getting linked by high-traffic sites only because of a rather careless and potentially harmful remark I made in the comments section, I would rather direct you to a more accurate post which I wrote on the DAMA-LIBRA result today, which better represents my thoughts and is more politically correct on the matter.


1. Peter Woit - April 16, 2008


There have been rumors that the DAMA-LIBRA experiment would be making claims of detection of dark matter in their talk at the conference today. Any news about this?

2. Mendo - April 16, 2008

Hi Peter, the DAMA-LIBRA talk is online here:


From a very quick read it look like they still see the annual modulation in their event rate (slide 24) and at a higher significance than before. Plenty about the stability of the experiment – which might affect the signal. No comparison with the current limits from CDMS and XENON – although I think given they see the same modulation the discrepancy, for WIMPs at least, is still there.



3. dorigo - April 16, 2008

Wow, you are really well informed, Peter.

Yes, I did listen to the talk about the DAMA-LIBRA experiment.
And indeed, they claim to have a 8.2-sigma signal of a yearly oscillation in the signal yield. This is compatible with a dark matter candidate with an energy release in the 3-6 keV range.

I must say I did not foresee to discuss that result, however, for two reasons. One is that the talk was poor – besides the bad English, the speaker presented far too heavy slides, and gave a rather sloppy presentation. She also did not allow questioners to speak, talking over them very aggressively as they asked for details of the efficiency curve – which rises steeply right in the region where a signal is seen – or about models that could fit the picture – the cut at 2 keV does not allow DAMA to discriminate different DM candidates. It made me mutter to my grad student, sitting next to me “small experiments make cocky speakers”.
The other reason is that I did not pay much attention to it. My fault, but when a 40′ talk is of poor quality my attention span quickly drops, and the wireless connection in the conference room unfortunately worked embarassingly well…

However, since you ask: yes, a signal is there. The fourier analysis shows a clear component with yearly frequency. I believe the result is on solid ground. I am more skeptical about the interpretation: yes, DM fits in. But I would not be too surprised if DAMA ended up having discovered a yearly variation in their photomultiplier response.


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7. Joe Franchetti--USA - April 18, 2008


8. patricia - April 20, 2008

I’m sorry I don’t know much about oscillations, but I love the building in the picture. 🙂

9. dorigo - April 20, 2008

Hi Patricia,

you can find more pictures of Palazzo Franchetti here


10. Vincenzo Antonuccio-Delogu - April 27, 2008

Wait a second: also the phase of the yearly signal is interesting. Maximum around June 2nd, minimum 6 months later. Exactly when the Earth is moving towards/away the Galactic center (see fig. 2 of their preprint arxiv:0804.2741)

Why should photomultipliers be in phase with the Earth’s motion w.r.t the Galactic center?

Maybe we could agree that they see a signal compatible with something symmetrically distributed w.r.t. our Galaxy.

My personal opionion is that their major problem is the lack of evidence from other passive detection experiments.

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