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Live feed of MiniBoone results seminar today! April 11, 2007

Posted by dorigo in internet, news, physics, science.

 MiniBoone is an experiment at Fermilab which is investigating neutrino oscillations and has the explicit purpose of clarifying the reality of an earlier  controversial signal found by the LSND collaboration.

The MiniBoone detector is a 12-meter sphere filled with 800 tons of mineral oil; its inner surface is lined with 1280 photomultiplier tubes which can detect the faint light signal produced by neutrino interactions. 240 additional tubes provide a veto to cosmic rays entering the active volume as charged tracks. The layout of the detector is shown below.

Located 500 meters downstream of the 8 GeV proton beam coming from the Fermilab Booster (a machine which is part of the Tevatron accelerating chain), MiniBoone collects a neutrino interaction every 20 seconds on average. The neutrinos are produced when the 8 GeV protons hit a beryllium target (a light material, which minimizes the divergence of the secondary beam). The kaons and pions produced in the high-intensity collisions decay to muons and muon neutrinos, and the latter travel to the tank in large numbers.

MiniBoone is looking for a signal of electron neutrinos: that would allow to determine the oscillation parameters of the conversion of muon to electron neutrinos in the range measured by LSND.  Electron neutrinos interacting with the mineral oil will produce an electron, which leaves a distinctly fuzzy cone of light around its trajectory by the Cherenkov effect. On the contrary, muons materialized by muon neutrino interactions will produce a better focused ring of light. The light is observed by photomultipliers, and offline analysis of the signals, allows a clean discrimination.

Readers familiar with the concept that neutrinos “oscillate” – that is, change their flavor periodically – might be confused to know that a whole experiment is dedicated to the task of confirming a past result by another collaboration. And it is easy to get lost while studying neutrino oscillation experiments: each of them is sensitive to different ranges of a few among many parameters describing the oscillation frequency and amplitude of processes changing each of the three neutrino flavors into any other.

That neutrinos could convert from one kind to another was something physicists had suspected for many years, due to several results dating as much as thirty years back which had shown a deficit of solar and atmospheric neutrinos. After the definitive confirmation of SuperKamiokande, everybody now believes neutrinos oscillate, but things appear only marginally better understood. How many neutrino species are there ? What is their mass ? What is the frequency of oscillation from one kind to another ? These are only a few of the many open questions that present-day neutrino experiments try to address.

Eyes will be wide open today at the MiniBoone seminar. And in fact, there is a lot at stake: the oscillation signal found by LSND is important to confirm or exclude, because if found true beyond doubt it would imply some startling new physics: the existence of a fourth family of neutrinos, or the inequality of neutrino and antineutrino masses. 

The graphs below show what LSND measured, in the plane of two parameters: the square of the mass difference between electron and muon neutrino on the y axis, and the squared sine of twice the angle theta describing the oscillation amplitude on the x axis. In blue is highlighted the region corresponding to the LSND signal. The wavy lines in the plot on the left show the area which MiniBoone will be able to investigate (left to right: exclusion region, 3-sigma, and 5-sigma discovery contours – meaning that if the parameters have a value on the right of the lines, they will be measured, while if they lie on the left of the leftmost line, MiniBoone will be useless to determine them, while excluding the LSND result). The ellipses in the plot on the right instead show how well MiniBoone expects to measure the parameters, if these have a value within the LSND preferred region.


The live stream of the seminar will be available  at this link from 11.00 to 12.30 CDT (16.00 GMT). I am very interested in the results, since I read in one of the pages of the Boone collaboration’s web site that

MiniBooNE is the first phase of the Booster Neutrino Experiment (BooNE); in this phase, neutrino oscillation measurements will be made with a single detector. If oscillations are observed, then MiniBooNE will be upgraded to stage two (BooNE) with a two-detector configuration. “

A few lines down, they make it even more clear:

If MiniBooNE verifies the LSND signal, then BooNE will proceed to its next stage: a second detector built at the appropriate neutrino source-detector distance. This distance will be determined so that the two-detector configuration can precisely measure the oscillation parameters, and search for CP and CPT violation.

That is to say: if today we see no signal of oscillations, forget the upgrade! Hmmm. Let me guess. I bet a dime they will not exclude the oscillation signal of LSND today, but show inconclusive but intriguing hints that muon neutrinos disappear into electron neutrinos or other ones. This, despite  rumours around… Anybody here who wants to take my dime bet?

UPDATE: I would have lost my bet… Although there is something in the disclosed results that does not fit with the model (and which might indeed represent an open door to more investigations and another detector). See a thorough explanation at the cosmic variance site .

UPDATE 2: The video of the seminar is available at http://vmsstreamer1.fnal.gov/VMS_Site_03/Lectures/MiniBooNE/070411Live/index.htm



1. Not Even Wrong » Blog Archive » MiniBooNE Results - April 11, 2007

[…] bother to write up something about the background of today’s MiniBooNE results, since Tommaso Dorigo has already done a better job than I ever could. He also provides a link to where the live feed of […]

2. DB - April 11, 2007

Thanks for the great explanation! Could you say more about why the LSND values imply “a fourth family of neutrinos, or the inequality of neutrino and antineutrino masses” ?

3. island - April 11, 2007

Anybody here who wants to take my dime bet?

One long-bet and a couple of vacations to far away countries has Dorigo digging in his pockets for spare betting change.

5 minutes til 11:00, and I wouldn’t bet against you, even if my name was Distler… 😉

4. onymous - April 11, 2007

From the streaming video site, I get “User Limit Exceeded. The maximum number of licensed users are connected. Try again later.” Sigh.

5. D - April 11, 2007
6. island - April 11, 2007

Where has all the antimatter gone?
VELO seeks the answer

Scientists from the Universities of Liverpool and Glasgow have completed work on the inner heart of an experiment which seeks to find out what has happened to all the antimatter created at the start of the Universe. Matter and antimatter were created in equal amounts in the Big Bang but somehow the antimatter disappeared resulting in the Universe, and everything in it, including ourselves, being made of the remaining matter.

Um… didya try looking in the *****rarefied***** vacuum?

I find this article to be as silly as it is interesting if what I said here is valid, and so I have to wonder when and if anybody is ever going to get a clue:


7. andrew - April 11, 2007

LSND results not confirmed. No signal seen. Standard Model rules! No new physics. (sigh).

8. dorigo - April 11, 2007

Hi all,

DB, I will post about it tomorrow, if I find the slides shown today – I would like to discuss the result in more detail. In a line here, the oscillation of muon neutrinos to electron neutrinos with values of delta_m squared and sin_2theta squared within the bounds of the LSND anomaly (blue region in the plots above) would fight the other, much better established, results on atmospheric and solar neutrinos. Since LEP established that only three neutrino species have weak couplings (by measuring the “invisible” width of the Z boson), there remains to invoke the oscillation of neutrinos into a sterile kind, or an even steeper difference in masses between neutrinos and antineutrinos. Sorry for the lack of clarity, will expiate tomorrow.

Island, you trust me too much – my prediction was based on my belief that taken singly, scientists can be completely honest, but large gatherings of scientists will naturally tend to deviate from the virtuous line to seek common good. I failed, apparently. But I will keep my dime this time.

D, thank you for the link. It is a good source of information.


9. island - April 11, 2007

taken singly, scientists can be completely honest

Unless your talking about the fact that the universe is “undeniably”, (per L. Susskind), observed to be strongly anthropically constrained. In which case, dogma rules the brain, my friend, and I’m not the first to say that, nor am I the last, since Paul Davies most recent book came out, he has also publicly stated his observation about willful *ideological* ignorance.

Carter called it, “anticentrist dogma”, and trust me, it lives in the hearts of individuals as well as via mass “anti-hysteria”.

/rant, and I’m sorry… but I leave an open challenge to that claim on my blog.

10. DB - April 11, 2007

Island (#6) re: antimatter in the “rarefied vacuum”:
If you are suggesting that antimatter (in amounts comparable to matter) lives in isolated pockets or spread throughout the vacuum of space, it is generally believed that it cannot be so. We would see characteristic annihilation radiation from all the overlap with interstellar dust.
See this article (originally by me!).

11. island - April 11, 2007

Wow, thanks for the reply and the link, David, but no, I’m afraid that “antimatter”, in this “state”, would not *yet* have characteristics that would enable annihilation.

There are a total of four very short unaddressed points by me that are attatched to this linked article, which address the point in language that changes what “we really know” if the unproven cosmological model that is ***assumed***… is not in effect.

I realize that there are some minor errors, for example in the second sentence of the first post, I said; In Einstein’s static model, G=0 when there is no matter.

In this case, it would have been more to the point to say, “when there is no *pressure*:


Tommasso, I aplogize for hijacking this thread for which there was a more appropriate place.

12. Top Posts « WordPress.com - April 12, 2007

[…] Live feed of MiniBoone results seminar today!  MiniBoone is an experiment at Fermilab which is investigating neutrino oscillations and has the explicit purpose of […] […]

13. Catherine Morgan - April 12, 2007

I think your site is great….although most is way over my head. But, I did link your site to a post I did today on the ATLAS Particle Detector. I’m hoping to continue to ad content to this post, so far I have two press articles, three YouTube videos, one picture, and the link to this site. If you happen to get a chance to check it out…..let me know if you have any suggestions.


14. Often in Error... - April 12, 2007

Holy (Neutrino) Trinity

Today the MiniBooNE collaboration released their first year results. For the press release, check here. For a full explanation, see that guest post at Cosmic Variance, or this one by Tommaso Dorigo. According to the…

15. Matti Pitkanen - April 12, 2007

The neutrino energies of LSND and MiniBoone are 60-200 MeV and 300-1500 MeV and oscillations in LSND mass range are found to be absent above 500 MeV. Evidence for oscillations is found below 500 MeV.

Hence LSND and MiniBooNE are consistent if one accepts that neutrino mass scale depends on its energy as TGD strongly suggests. For details see the posting at my blog page.

Matti Pitkanen

16. dorigo - April 12, 2007

Hi Matti,

I disagree about the “evidence for oscillations below 500 MeV”. They simply stated their low energy data is harder to understand, and took it off their analysis. But in fact, the excess at low energy cannot be fit by any oscillation parameters, because the points rise too steeply.

Give MiniBoone time, and they will have a statement about those data points. So far, it is much too early to say anything, if they themselves have nothing to say – they were honest enough to show the data as it was coming out of the box, without further filtering of what they feel they do not understand well.


17. dorigo - April 12, 2007

Hi Catherine,

I checked your site, but it either does not load well or I am missing something. Will check back tomorrow.


18. Jonathan Vos Post - April 12, 2007

“Matter and antimatter were created in equal amounts in the Big Bang but somehow the antimatter disappeared resulting in the Universe, and everything in it, including ourselves, being made of the remaining matter.”

Which is why Ting and about 500 other people, including Michael Salamon at NASA HQ, spent over a gigabuck building an antinucleus detector to fly in the Space Station. If it detected a single, say, anti-iron nucleus, that would strongly imply an antistar making anti-iron by antinucleosynthesis and dispersing it when it went antisupernova. But NASA in its infinute wisdom has decided not to fly the experiment, on the basis that all remaining Shuttle flights are needed to finish building the ISS, which won’t do any science. Or something.

I’d long ago proposed neutrino detectors on the Moon, to give a longer baseline for neutrino oscillation experiments.



“Mercury polar ice could provide neutrino detection opportunities…”

19. dorigo - April 13, 2007

Hi Jonathan,

I guess “infinute” is not a typo 😉 or maybe it is a freudian slip ?

Your ideas are interesting but expensive! HEP does not have nearly that kind of dough. The moon will be colonized for other purposes than counting neutrino cross sections, and as for Mercury, it’s a great idea to think about exploring it, but it does not seem to be in the agenda…


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