Subscribe free to our newsletters via your
. 24/7 Space News .


Subscribe free to our newsletters via your




















TIME AND SPACE
Beam-beam compensation scheme doubles proton-proton collision rates
by Staff Writers
Upton NY (SPX) Jan 05, 2016


Brookhaven Lab accelerator physicist Wolfram Fischer stands next to the electron lensing apparatus at the Relativistic Heavy Ion Collider (RHIC), a particle accelerator/collider at the US Department of Energy's Brookhaven National Laboratory. Image courtesy Brookhaven National Laboratory. For a larger version of this image please go here.

Accelerator physicists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have successfully implemented an innovative scheme for increasing proton collision rates at the Relativistic Heavy Ion Collider (RHIC). More proton collisions at this DOE Office of Science User Facility produce more data for scientists to sift through to answer important nuclear physics questions, including the search for the source of proton spin.

"So far we have doubled the peak and average 'luminosity'-measures that are directly related to the collision rates," said Wolfram Fischer, Associate Chair for Accelerators of Brookhaven's Collider-Accelerator Department and lead author on a paper describing the success just published in Physical Review Letters. And, he says, there's potential for further gains by increasing the number protons from the injectors even more.

Colliding polarized protons
RHIC is the world's only polarized proton collider, capable of sending beams of protons around its 2.4-mile-circumference racetrack with their internal magnetic axes (also known as spins) aligned in a chosen direction. Colliding beams of such "spin polarized" protons and manipulating the spin directions gives scientists a way to explore how their internal building blocks, quarks and gluons, contribute to this intrinsic particle property.

Data at RHIC have revealed that both quarks and gluons make substantial contributions to spin, but still not enough to explain the total spin value. More data will help resolve this spin mystery by reducing uncertainties and allowing nuclear physicists to tease out other unaccounted for contributions.

But getting more protons to collide is an ongoing challenge because, as one beam of these positively charged particles passes through the other, the particles' like charges make them want to move away from one another.

"The strongest disturbance a proton experiences when it travels around the RHIC ring is when it flies through the other proton beam," Fischer said. "The result of the positive charges repelling is that the protons get deflecting kicks every time they fly through the oncoming beam."

Opposite charge produces opposite push
The size of the repulsive kick depends on where the proton flies through the beam, with protons about halfway from dead center to the outside edge of the beam's cross-section experiencing the largest outward push. Particles closer to the center or the outer edge of the cross-section experience less repulsion.

Because of the variable shape of this effect-increasing to a peak and then decreasing with distance from the beam's center-it's impossible to correct using magnets. "The magnetic field strength in magnets increases steadily from the center out," Fischer said.

So instead, the scientists turned to using oppositely charged particles to produce a compensating push in the opposite direction.

"We've implemented electron lensing technology to compensate for these head-on beam-beam effects," Fischer said.

Essentially, they use an electron gun to introduce a low-energy electron beam into a short stretch of the RHIC accelerator. Within that stretch, the electrons are guided by a magnetic field that keeps them from being deflected by the more energetic protons. As the protons pass through the negatively charged electron beam, they experience a kick in the opposite direction from the repulsive positive charge, which nudges the protons back toward the center of the beam.

"It's not a glass lens like you'd find in a camera," Fischer said, "but we call the technique 'electron lensing' because, like a lens that focuses light, the electron beam changes the trajectory of the protons flying through it."

Riding the optical wave
The scientists also take advantage of certain "optical" properties of RHIC's particle beams to ensure the method's efficacy.

"Ideally you would like to produce these compensating pushes right where the collisions happen, within the STAR and PHENIX detectors," Fischer said. "But then the experiments wouldn't work anymore. So we placed the electron lenses, one on each beam, at a certain distance from the detectors-called the optical distance-where they have an effect at the same point in the 'phase' of the particle beam that's inside the detectors."

Like a wave of light or sound that oscillates up and down in amplitude at a given frequency, the particles that travel around RHIC also oscillate a tiny bit. As long as the nuclear physicists know the frequency of the oscillations and give their electron-lensing kicks at the same point in that oscillation that the particles reach within the detector, the effect will compensate for the proton repulsion the particles experience at that distant location.

So far, the scientists have doubled the proton-proton collision rates at RHIC. They could potentially get even higher gains by increasing the number of protons injected into the machine.

"The key challenge will be to maintain the high degree of polarization the experiments need to explore the question of proton spin," Fischer said. But he insists there is clear potential for even higher proton-proton luminosity.

.


Related Links
Brookhaven National Laboratory
Understanding Time and Space






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
TIME AND SPACE
Surface physics: How water learns to dance
Vienna, Austria (SPX) Dec 24, 2015
Perovskites are materials used in batteries, fuel cells, and electronic components, and occur in nature as minerals. Despite their important role in technology, little is known about the reactivity of their surfaces. Professor Ulrike Diebold's team at TU Wien (Vienna) has answered a long-standing question using scanning tunnelling microscopes and computer simulations: How do water molecule ... read more


TIME AND SPACE
Rare full moon on Christmas Day

LADEE Mission Shows Force of Meteoroid Strikes on Lunar Exosphere

XPRIZE verifies moon express launch contract, kicking off new space race

Gaia's sensors scan a lunar transit

TIME AND SPACE
NASA suspends March launch of InSight mission to Mars

University researchers test prototype spacesuits at Kennedy

Marshall: Advancing the technology for NASA's Journey to Mars

Opportunity positioned on steeper slopes for another Martian winter

TIME AND SPACE
Gadgets get smarter, friendlier at CES show

Astronauts Tour Future White Room, Crew Access Tower

ISRO's year in review 2015

Celebrity chefs create gourmet delights for astronauts

TIME AND SPACE
Chinese rover analyzes moon rocks: First new 'ground truth' in 40 years

Agreement with Chinese Space Tech Lab Will Advance Exploration Goals

China launches new communication satellite

China's indigenous SatNav performing well after tests

TIME AND SPACE
British astronaut dials wrong number on Xmas call from space

Space Station Receives New Space Tool to Help Locate Ammonia Leaks

Two whacks is all it takes for spacewalk repair

Unscheduled spacewalk likely on Monday

TIME AND SPACE
45th Space Wing launches ORBCOMM; historically lands first stage booster

SpaceX rocket landing opens 'new door' to space travel

NASA orders second Boeing Crew Mission to ISS

ESA and Arianespace ink James Webb Space Telescope launch contract

TIME AND SPACE
Nearby star hosts closest alien planet in the 'habitable zone'

ALMA reveals planetary construction sites

Monster planet is 'dancing with the stars'

Exoplanets Water Mystery Solved

TIME AND SPACE
Transition metal catalyst prompts 'conjunctive' cross-coupling reaction

New technique offers strong, flawless 3-D printed ceramics

UCLA researchers create exceptionally strong and lightweight new metal

Japanese research team earns right to name Element 113




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News








The content herein, unless otherwise known to be public domain, are Copyright 1995-2016 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.