Of Particular Significance

Tag: CERN

It’s been quite a week… Spectacular northern lights for hours on Thursday night. A great comet in the evening skies (though so far I’ve have only caught glimpses, thanks to atrocious viewing conditions.) And now, I’m at CERN (the pan-European particle physics laboratory) for the first time since the pandemic began. I’ll be giving a talk at a conference of CMS experimenters. (CMS and ATLAS are the two general purpose experiments at the Large Hadron Collider [LHC].)

The topic of the workshop is a novel technique called “Level-1 Scouting” — though it isn’t really about “scouting” for anything. It has to do with evading the strait-jacket of the trigger, an essential feature of data gathering at each of the LHC experiments. With tens of millions of collisions per second, the data flood at CMS is too great, and only a tiny fraction of these collisions can be stored. The trigger decides real-time which ones to keep and which ones to discard forever. That’s been the basic rule since the LHC began running.

But this rule no longer applies, thanks to new technology and human ingenuity. CMS now uses level-1 scouting to record sketchy information about every single collision that happens in their detector. LHCb, with a smaller detector, was the first to try something along these lines. ATLAS is on a parallel track. These developments have the potential, looking ahead, to substantially enhance the capability of these detectors. More about this after I’ve given my talk.

Auroras after sunset. (These were as bright to the naked eye)
Comet A3 after sunset. (Brighter than to the naked eye.)

Post-sunset light over CERN. (As to the naked eye.)

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON October 14, 2024

A number of people have asked me my opinion concerning CERN‘s proposal for a new, larger and more powerful particle physics collider… or rather, two completely different colliders that would operate in the same tunnel:

  • Phase 1 (two to three decades from now): an electron-positron collider targeted at the detailed physics of Higgs bosons, Z bosons, W bosons and top quarks, using them to search for subtle high-energy phenomena and for rare but dramatic low-energy phenomena;
  • Phase 2: (five to six decades from now) an exploratory proton-proton collider, like the Large Hadron Collider [LHC] but with a higher collision energy, and therefore capable of making discoveries of particles that either have higher mass or a lower production rate than what LHC can handle.
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Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON February 6, 2024

A few days after Russia invaded Ukraine (I will not call it a “war,” as that might offend Czar Vlad and his friends) for the nth time, my thoughts turned to the consequences for the CERN laboratory and for upcoming research at the Large Hadron Collider [LHC].   It was clear that Putin would blackmail Europe using his oil and gas supplies, leading to a spike in energy prices and a corresponding spike in CERN’s budget.

Of course I didn’t foresee the heat waves and drought that have swept Europe, or the maintenance problems at France’s nuclear plants, which have made the energy crisis that much worse.  (Even though global climate change is now quite obvious, and the trends are partially predictable, one can’t predict what will happen in any given year.)  I am not familiar with the budgetary consequences of these higher energy prices for CERN operations, but they cannot be good.

(more…)
Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON September 6, 2022

Day 2 of my visit to CERN (host laboratory of the Large Hadron Collider [LHC]) was a pretty typical CERN day for me. Here’s a rough sketch of how it panned out:

  • 1000: after a few chores, arrived at CERN by tram. Worked on my ongoing research project #1. Answered an email about my ongoing research project #2.
  • 1100: attended a one hour talk, much of it historical, by Chris Quigg, one of the famous experts on “quarkonium” (atom-like objects made from a quark or anti-quark, generally referring specifically to charm and bottom quarks). Charmonium (charm quark/antiquark atoms) was discovered 40 years ago this week, in two very different experiments.
  • 1200: Started work on the talk that I am giving on the afternoon of Day 3 to some experimentalists who work at ATLAS. [ATLAS and CMS are the two general-purpose experimental detectors at the LHC; they were used to discover the Higgs particle.] It involves some new insights concerning the search for long-lived particles (hypothesized types of new particles that would typically decay only after having traveled a distance of at least a millimeter, and possibly a meter or more, before they decay to other particles.)
  • 1230: Working lunch with an experimentalist from ATLAS and another theorist, mainly discussing triggering, and other related issues, concerning long-lived particles. Learned a lot about the new opportunities that ATLAS will have starting in 2015.
  • 1400: In an extended discussion with two other theorists, got a partial answer to a subtle question that arose in my research project #2.
  • 1415: Sent an email to my collaborators on research project #2.
  • 1430: Back to work on my talk for Day 3. Reading some relevant papers, drawing some illustrations, etc.
  • 1600: Two-hour conversation over coffee with an experimentalist from CMS, yet again about triggering, regarding long-lived particles, exotic decays of the Higgs particle, and both at once. Learned a lot of important things about CMS’s plans for the near-term and medium-term future, as well as some of the subtle issues with collecting and analyzing data that are likely to arise in 2015, when the LHC begins running again.

[Why triggering, triggering, triggering? Because if you don’t collect the data in the first place, you can’t analyze it later!  We have to be working on triggering in 2014-2015 before the LHC takes data again in 2015-2018]

  • 1800: An hour to work on the talk again.
  • 1915: Skype conversation with two of my collaborators in research project #1, about a difficult challenge which had been troubling me for over a week. Subtle theoretical issues and heavy duty discussion, but worth it in the end; most of the issues look like they may be resolvable.
  • 2100: Noticed the time and that I hadn’t eaten dinner yet. Went to the CERN cafeteria and ate dinner while answering emails.
  • 2130: More work on the talk for Day 3.
  • 2230: Left CERN. Wrote blog post on the tram to the hotel.
  • 2300: Went back to work in my hotel room.

Day 1 was similarly busy and informative, but had the added feature that I hadn’t slept since the previous day. (I never seem to sleep on overnight flights.) Day 3 is likely to be as busy as Day 2. I’ll be leaving Geneva before dawn on Day 4, heading to a conference.

It’s a hectic schedule, but I’m learning many things!  And if I can help make these huge and crucial experiments more powerful, and give my colleagues a greater chance of a discovery and a reduced chance of missing one, it will all be worth it.

Picture of POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON November 12, 2014

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