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Neutrino Hunters Hack Chat

Patrick Allison

Wednesday, January 17, 2024 12:00 pm PST Local time zone:
Hack Chat
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Patrick Allison will host the Hack Chat on Wednesday, January 17 at noon Pacific.

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It's a paradox of science that the biggest of equipment is needed to study the smallest of phenomena. The bestiary of subatomic particles often requires the power and dimension of massive accelerators to produce, and caverns crammed with racks full of instruments to monitor their brief but energetic lives. Neutrinos, though, are different. These tiny, nearly massless, neutral particles are abundant in the extreme, zipping through space from sources both natural and artificial and passing through normal matter like it isn't even there. 

That poses a problem: how do you study something that doesn't interact with the stuff you can make detectors out of? There are tricks that neutrino hunters use, and most of them use very, VERY big instruments to do it. Think enormous tanks of ultrapure water or a cubic kilometer of Antarctic ice, filled with photomultiplier tubes to watch for the slightest glimmer of Cherenkov radiation as a neutrino passes by, or a balloon hovering 100 km above Antarctica using the entire continent as a detector.

Neutrino hunting is some of the biggest of Big Science, and getting all the parts to work together takes some special engineering. Patrick Allison has been in the neutrino business for decades, both as a physicist and as the designated guru who keeps all the electronics humming. He'll join us on the Hack Chat to talk about the neutrino hunting trade, and what it takes to keep the data flowing.

Banner image: Daderot, CC0, via Wikimedia Commons

  • Hack Chat Transcript

    Tom Nardi01/17/2024 at 21:30 0 comments

    Dan Maloney  3:00 PM
    Not sure I've seen him check in yet, though. You out there Pat?
    Patrick Allison  3:01 PM
    I'm here now! Internet connection literally went down at 3 exactly. Fun.
    Dan Maloney  3:01 PM
    Good timing! Welcome aboard
    Dan Maloney  3:01 PM
    Cold and snow there? We're getting womped
    Patrick Allison  3:02 PM
    I am so not going to be able to compete with live event detector tracks, FWIW
    Patrick Allison  3:02 PM
    Yeah, everything's closing due to the cold. Sub-zero wind chills. Fun.
    Dan Maloney  3:03 PM
    No worries at all, Hack CHats are about cool people doing cool stuff, and you've got that going. Tell us a little about how you got where you are
    Patrick Allison  3:04 PM
    Sure! My freshman year at Penn State I apparently impressed my freshman physics prof, who recommended me to Prof. Jim Beatty, who was a new hire, starting up the particle astrophysics group. That got me started into balloon experiments, cosmic ray astrophysics, and eventually my PhD dissertation on the Pierre Auger Observatory.
    Patrick Allison  3:05 PM
    Might seem like a leap from cosmic rays to neutrinos, but the two fields are *very* intrinsically linked - and from there it led into working on the Antarctic Impulsive Transient Antenna, which is a balloon experiment looking for ultrahigh energy (> 10^18 eV) neutrinos in the Antarctic ice
    Darryl Masson  3:06 PM
    Some might argue that neutrinos *are* the most interesting cosmic rays
    kjansky1  3:06 PM
    Do you know if we are closer to determining the relative masses of the e,m & t neutrinos and do you think the correlate with the masses of their corresponding leptons?
    Patrick Allison  3:06 PM
    Absolutely! In fact the reason I say they're intrinsically linked is that at the *highest* energies - the one's we're looking for - we know that the neutrinos exist because the cosmic rays we see have to produce them.
    Patrick Allison  3:07 PM
    For the first part of that question - how close are we to getting the absolute masses - definitely can't answer that. There are a lot of experiments out there trying to do so, but it's very, very hard.
    Patrick Allison  3:08 PM
    For the second part, I think it's safe to say that no, neutrino masses are *not* linked to the masses of the e/mu/tau at all. There's just far, far too big a gap between them
    Darryl Masson  3:08 PM
    Has KATRIN released anything recently? I know their sensitivity is no longer competitive, but they're the only big name in town for a direct mass measurement
    The # of #neutrinos observed in #Super-Kamiokande is ~30/day. In terms of prob. it may be nearly impossible to find neutrinos on this monitor. Almost all events are cosmic ray muon events." One was detected moments after I opened the visor on my phone for the first time! You can access the public real time visor at https://www-sk.icrr.u-tokyo.ac.jp/realtimemonitor/ The neutrinos collide with the matter inside the huge tank and generate ring shaped light beams that propagate in a cone. This light is detected by an array of photomultipliers. A good project would be replicating the detector array with RGB LEDs, so a small computer would access the web image and display the current state of the detector.
    Patrick Allison  3:09 PM
    I haven't seen anything since 2022, but I think they're still running? So maybe in the next few years. But yeah, it'd be surprising if they found something.
    Thomas Shaddack  3:09 PM
    There are arrays of WS2812b-like LEDs that could be easily adapted to the purpose.
    kjansky1  3:10 PM
    OK how about the existence of the possibly 4th neutrino and do you think neutrinos are Majorama particles?
    ...
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Fred Schimmel wrote 01/17/2024 at 19:47 point

There also is a big neutrino experiment called KM3net, based on detection of secondary events from neutrino interaction with sea-water on about 3 km depth in the Mediterranean, South of the French coast and near Sicily. A third location near the coast of Greece is under consideration. The design foresees the monitoring of a cubic kilometer seawater with anchored strings of 13 balls, each equipped with ~30 photo multipliers.

The received signals are modulated on light with a vast set of wavelengths, to create the number of communication channels to transfer the vast amount of data.

For more info: https://www.km3net.org/

  Are you sure? yes | no

synaptic.axon wrote 01/17/2024 at 17:15 point

Have you looked at the ideas proposed by https://energywavetheory.com/ regarding Neutrinos as the basis of all matter?

  Are you sure? yes | no

synaptic.axon wrote 01/17/2024 at 17:02 point

How concerned are you about the health implications from Galactic Cosmic Ray secondary particles in human beings and other life on Earth?  What steps can we take to shield ourselves from this other than thick concrete or lead?  Is there an electrostatic method?

  Are you sure? yes | no

synaptic.axon wrote 01/17/2024 at 16:59 point

What is the best bet for an amateur scientist to visualize neutrinos?

There should be some from muon decay in a cloud chamber, even if we can't see them.

Are there any materials that an amateur could use to detect them, say something with a very high Debye Temperature such as Sapphire or Diamond?

  Are you sure? yes | no

Patrick Allison wrote 01/20/2024 at 17:32 point

The technology used for neutrino detectors isn't really neutrino specific - they're "neutrino detectors" because they're particle detectors built in places where  either the neutrino flux is super high (not accessible to amateur scientists) or the background particle flux is super low (so again, not accessible to amateur scientists).

Can you make small detectors with high neutrino sensitivity? Yes, and they do, with something called coherent neutrino scattering. Does this help for amateur detection? No, because those detectors *still* need to be in high-flux or low-background areas, because they're not *just* neutrino detectors.

So... there isn't really a "best bet." For just casual observation you'd want an imaging particle detector in a magnetic field, but you'd be waiting a very long time to see a characteristic track in that case, and you'd still probably be fooled by some background.

  Are you sure? yes | no

synaptic.axon wrote 01/17/2024 at 16:57 point

Have you been able to localize the origin of the extra-Solar neutrinos striking Earth?

If Sol's mean interaction distance is 35 light years, what is the energy level and interaction distance of neutrinos coming from say Betelgueuse, Tau Ceti, or other stars in the Local Group?  How old are the neutrinos?

  Are you sure? yes | no

synaptic.axon wrote 01/17/2024 at 16:54 point

What are the military implications of the billion dollar investment into neutrino detection in Antarctica?  With the other detectors around the globe, are you now able to trilaterate all nuclear reactors on Earth (power plants, submarines, wrecked alien craft)?

  Are you sure? yes | no

Patrick Allison wrote 01/20/2024 at 17:09 point

"billion dollar investment into neutrino detection in Antarctica?"

You have a *very* inflated idea as to how much has been invested into neutrino detection in Antarctica. The largest one would be IceCube, which is maybe a third of a billion, and the others are all single-millions.

In addition, reactor neutrinos and astrophysical neutrinos are very, very different energy scales. Reactor neutrinos are primarily MeV-scale. A "mega-detector" to monitor for all nuclear reactors might be possible, but it would be tough.

  Are you sure? yes | no

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