60 questions · 39 almanac · 0 findings

Particle Accelerators and Detectors

Machines and instruments used to probe subatomic particles.

Almanac A Contrail for the Invisible
  • How does a cloud chamber make the path of a charged particle visible?
  • Why was Wilson's cloud chamber so important for physics after 1927?
Almanac A Track That Bent the Wrong Way
  • How did the curvature of a cloud chamber track reveal that Anderson had found a positively charged, lightweight particle?
Almanac Who Ordered That?
  • How did the curvature of the mystery particle's track in a magnetic field rule out both a proton and an electron?
Almanac A Spiral Instead of a Mile
  • Why did accelerating particles in a straight line become impractical for physicists in the early 20th century?
  • How does bending a particle's path into a spiral let it reach higher speeds without a longer machine?
  • What medical treatments eventually grew out of the cyclotron's ability to produce particle beams?
Almanac A Camera That Waits for Something to Happen
  • How did Blackett get a cloud chamber to photograph only the moments worth capturing?
  • What role did Geiger counters play in triggering the camera shutter?
  • What earlier discovery had the cloud chamber already enabled before Blackett's improvement?
Almanac A Nucleus Comes Apart on a Cambridge Bench
  • How did Cockcroft and Walton's accelerator split a lithium nucleus using a beam of protons?
  • Why did Cockcroft and Walton's earlier attempts at building an accelerator fail before their 1932 success?
Almanac God, It Turns Out, Plays Dice
  • How does Walther Bothe's coincidence method let experimenters tell which particle detections belong to the same event?
Almanac A Twin for Every Particle
  • How did Segrè and Chamberlain use the Bevatron to distinguish antiprotons from the flood of ordinary collision debris?
Almanac A Trail of Bubbles, Not Vapour
  • Why did the cloud chamber's supersaturated vapour struggle to keep up with the particles physicists wanted to study?
  • How does a superheated liquid reveal the path of a charged particle passing through it?
  • What is the real origin story behind Glaser's bubble chamber, and how does it differ from the beer-glass legend?
  • What new particles did bubble chambers make it possible to discover through the 1960s and 70s?
Almanac Why Anything Weighs Anything
  • How many years passed between Higgs's 1964 paper and the experimental confirmation of the Higgs boson at the LHC?
Almanac Two Forces Turn Out to Be One
  • What made the W and Z boson mass predictions such a bold bet for the theory?
  • How did CERN's 1983 discovery of the W and Z bosons confirm the theory?
Almanac The Theory Was Right, to the Kilogram
  • How did Carlo Rubbia and Simon van der Meer use proton-antiproton collisions at the CERN Super Proton Synchrotron to find the W and Z bosons?
  • What is stochastic cooling, and why was it necessary to make the antiproton beam usable?
Almanac Antiprotons, Tamed Without a Touch
  • How does stochastic cooling let physicists corral a chaotic beam of antiprotons without touching any individual particle?
  • Why was accumulating antiprotons in useful quantities considered nearly impossible before van der Meer's technique?
Almanac A Reef Beneath the Water
  • What did the SLAC experiments observe when electrons bounced backward off protons, and why did that rule out a smooth proton?
  • Why couldn't quarks simply be seen directly in a detector, and what had to be inferred instead?
Almanac A Railway Timetable for Particles
  • How did Georges Charpak's multiwire proportional chamber work?
  • Why were bubble chambers inadequate for the particle rates that colliders were reaching?
  • What later collider experiments relied on designs descended from Charpak's chamber?
Almanac A Ghost Particle, Finally Caught
  • How did Frederick Reines and Clyde Cowan manage to detect a particle that barely interacts with anything?
  • What in Martin Perl's SLAC data pointed to a completely new charged lepton rather than an error in the apparatus?
Almanac A Billion People Watch a Ring Switch On
  • What chain of events, starting with a faulty electrical connection, caused the LHC to shut down just nine days after its first beam?
  • How long did repairs from the 2008 helium leak keep the LHC out of commission?
  • What major discovery did the LHC make once it returned to operation in 2009?
Almanac A Field No One Could See Yet
  • Why did it take nearly fifty years and a seventeen-mile collider to confirm the Higgs boson?
  • What did the bump at 125 GeV in the LHC data actually show physicists?
Almanac The Reluctant Owner of a Field
  • Why did confirming the existence of the Higgs boson take forty-eight years and require the Large Hadron Collider?
Almanac Thirteen Thousand Names on One Prize
  • What discoveries did the ATLAS, CMS, ALICE, and LHCb collaborations at the LHC contribute to over their cumulative history?
  • How large is the collaboration behind the LHC experiments, and what does that scale of coordination require?