Accelerator operator Salah Chaurize performs a diagnostic test on the RFQ at Fermilab. Courtesy Fermilab.
Fermilab has taken a major step toward laying the technical groundwork for Project X by creating a new test beam for superconducting radiofrequency cavities and components.
Earlier this month, the High Intensity Neutrino Source (HINS) collaboration successfully accelerated a proton beam to 2.5 MeV in a radiofrequency quadrupole accelerator, or RFQ, for the first time at Fermilab.
“This will provide a beam platform to facilitate development of components critical for Project X,” says Bob Webber, APC/HINS department head.
The 10-foot-long RFQ serves as the driving force of a proton linac in the Meson Detector Building. It will enable collaborators to test the ground-breaking application of superconducting radiofrequency (SRF) cavities for the acceleration of a high-intensity proton beam from very low energies.
Gary Lauten, a radiation safety officer, observes while Bob Webber, APC/HINS Department head, and Bruce Hanna, engineering physicist, inspect the RFQ beamline at Fermilab. Courtesy Fermilab.
"On the first attempt the RFQ achieved the design acceleration," says Giorgio Apollinari, head of Fermilab's Technical Division. "This type of technical achievement is the groundwork that will support Fermilab’s research in the second decade of this century."
The RFQ uses strong electrical fields to accelerate ionized hydrogen into a low-energy proton beam. That beam will then accelerate through 18 copper, room-temperature cavities up to a minimum energy compatible with the superconducting cavities that make up the remainder of the linac. The SRF cavities use stored radiofrequency energy to accelerate particles as they pass.
In February 2009, the HINS collaboration successfully tested the first 325-MHz single-spoke resonator SRF cavity. Collaborators expect to become the first in the world to accelerate beam through this type of cavity using the RFQ as a power source. This would lay the ground work for stringing many cavities together to create a unique linear accelerator for discovery at the intensity frontier.
This new use of SRF technology enables efficient production of the intense proton beam that will give Project X its versatility as a front end for a muon collider or a neutrino factory. SRF cavities can effectively increase the particle beam energy while minimizing the required electrical power by all but eliminating electrical resistance.
Collaborators from Fermilab and Argonne national laboratories designed the RFQ system to meet anticipated Project X physics needs in early 2006. AccSys Technology Inc., a private manufacturing firm, supplied the mechanical design and fabrication work.
Jim Steimel, engineer, inspects the RFQ beam absorber. Courtesy Fermilab.
“It’s not like there is only one small piece of the lab working on this,” Webber says. “It is the result a great deal of effort from the Technical Division, the Accelerator Division and the Accelerator Physics Center.”
Along with testing SRF cavities, the RFQ will provide beam to test other components of Project X, including beam diagnostic equipment and the beam chopper that determines the time structure within the beam pulses.
The HINS R&D program comprises contributions from Fermilab, Argonne, Lawrence Berkeley National Laboratory, Brookhaven National Laboratory and the Oak Ridge Spallation Neutron Source.
For the test linac, Berkeley provided two of the non-superconducting cavities and Brookhaven devised prototype beam instrumentation.
