A Big Future for Small Accelerators

National Security on the Move with High Energy Physics
geddes-editedBy Theresa Duque
Scientists are developing a portable technology that will safely and quickly detect nuclear material hidden within large objects such as shipping cargo containers or sealed waste drums. The researchers, led by Berkeley Lab scientists, have been awarded over $10 million from the Department of Energy’s National Nuclear Security Administration (NNSA) Defense Nuclear Nonproliferation R&D Office to combine the capabilities of conventional building-size research instruments with the transportable size of a truck for security applications on the go. Continue reading A Big Future for Small Accelerators


Expected sensitivity studies for gluino and squark searches using the early LHC 13 TeV

… Run-2 dataset with the ATLAS experiment

The current searches in the LHC Run-1 dataset have yielded sensitivity to TeV scale gluinos, as well as to third generation squarks in the hundreds of GeV mass range. The discovery reach in Run-2 is expected to be greatly enhanced due to the large increase in the LHC centre-of-mass collision energy from 8 TeV to 13 TeV. This document presents sensitivity studies for gluino pair production and bottom squark pair production with a full simulation of the ATLAS detector at a centre-of-mass energy of 13 TeV. Results are shown for an integrated luminosity of 1, 2, 5 and 10 fb−1
Read more at https://cds.cern.ch/record/2002608/files/ATL-PHYS-PUB-2015-005.pdf

Muon Detection with a Ring Imaging Cerenkov Radiation Detector

A team of two undergraduate students and their adviser at Missouri Southern State University has built a type of particle detector usually found only at large research organizations like CERN.
Using a little more than five hundred dollars worth of off-the-shelf parts, the team constructed a ring-imaging Cherenkov (RICH) detector, which can identify electronically charged subatomic particles by analyzing the eerie glow of light the particles emit when they travel faster through a material than the speed of light in that material.
The project was born from the desire to help students without access to expensive facilities perform hands-on experiments in particle physics, said Kristina Pritchard, a physics student at Missouri Southern State University in her junior year. Pritchard collaborated with fellow student Shemaiah Khopang and faculty advisor David McKee to build the detector.
Pritchard will present the team’s design on Saturday, April 11 at the APS April Meeting in Baltimore, Maryland.
The core of the inexpensive RICH detector is a commercial digital camera made by Sony. Pritchard and Khopang took apart the camera and inserted a piece of material with an index of refraction lower than glass. Finding the right material was the toughest part of the project, said Pritchard. The team ultimately used a piece of magnesium fluoride, which has an index of refraction of n=1.37, compared to typical glass indices of refraction that range from n=1.5 to n=1.6. The new material was needed to lower the angle of the emitted Cherenkov radiation in order to see the ring of light.
Another challenge came from an unexpected source: 1.6mm diameter screws. Once the team disassembled the camera, they realized they needed additional screws to put it back together, but the screws they needed were not a size typically available in the U.S.
With persistence and luck, Prichard located a rare stash of 1.7mm screws at a local hardware store that were just small enough to do the job. “Boy, have I felt like MacGyver through this process!” she said.
The team plans to validate their detector by measuring the cosmic muon energy spectrum. Muons are a type of negatively charged elementary particle. Most muons that reach earth are formed when cosmic rays collide with molecules in the atomosphere. “About 1 muon goes through your hand each second,” Prichard said.
The team has finished modifying the camera and Prichard and Khopang have already spotted their first photon ring. They will continue to gather data in the months ahead.
“When we first saw the photon ring we started jumping up and down,” Prichard said. “Assuming all goes well, we hope to share this design with universities all around the world so that others with little to no financial help from the school will be able to experience hands-on research in particle physics.”
…. Read more at http://phys.org/news/2015-04-diy-particle-physics.html

Popper’s experiment realized again—but what does it mean?

Illustration of Popper’s experiment realized with randomly paired photons in a thermal state. In the second set-up, there is no “slit B” for the photon on the right. The new results show that this photon is not affected by a measurement on the left photon (which does travel through a slit), in agreement with Popper’s prediction. Credit: Tao Peng, et al. ©2015 EPLA

Illustration of Popper’s experiment realized with randomly paired photons in a thermal state. In the second set-up, there is no “slit B” for the photon on the right. The new results show that this photon is not affected by a measurement on the left photon (which does travel through a slit), in agreement with Popper’s prediction. Credit: Tao Peng, et al. ©2015 EPLA

Like Einstein, the philosopher Karl Popper was a realist who was deeply bothered by some of the odd implications of quantum mechanics. Both Popper and Einstein disliked the idea in Heisenberg’s uncertainty principle, for instance, that precisely measuring one property of a particle means that the particle’s conjugate property is completely undetermined. This idea undermines the basic principle of common-sense realism: that every particle’s properties must have precise pre-existing values, which do not depend on being measured.
Both Popper and Einstein proposed thought experiments critiquing the uncertainty principle. But while Einstein, Podolsky, and Rosen’s EPR experiment is quite famous, Popper’s experiment is not as widely known.

Popper first published his proposed experiment in 1934, and in 1999, physicists Yoon-Ho Kim and Yanhua Shih realized Popper’s experiment for the first time. In what came as a surprise to many, their results agreed with Popper’s predictions, yet are not generally considered to be a true violation of the uncertainty principle, as Popper believed. The findings ignited a great deal of critique, both of Popper’s original ideas and how they might be realized and interpreted.
Now in a new study published in EPL, Shih and coauthors at the University of Maryland in Baltimore and Oakland Community College in Waterford, Michigan, have again realized Popper’s experiment using a different approach. Once again, their results agree with Popper’s predictions, yet still do not violate the uncertainty principle. However, the researchers explain that the results do reveal a concern about nonlocal interference, as the observations suggest that a pair of particles is instantaneously interfering with itself, even across large distances…
… Read more at http://phys.org/news/2015-01-popper-againbut.html

Read also: Popper’s Experiment and the Uncertainty Principle