First experiments receive beam in the new Irradiation Test Area

The new Irradiation Test Area has met a milestone: It has begun transporting a high-intensity proton beam to the very first set of user experiments.

On Jan. 11, the beam began irradiating the first user samples from the CMS and ATLAS High-Luminosity Large Hadron Collider upgrade projects. The ITA will play a critical role in these projects and others to come. The beginning of operations ushers in a new era of instrumentation development in high-energy physics.

The ITA program gives experimenters an R&D facility to study the effects of radiation and radiation damage on detector components and materials. Such studies are necessary for assessing component performance in the extreme environments of, for example, the High-Luminosity LHC. Radiation is an expected outcome of the multitude of energetic particles produced in the physics collisions, colliding with and ionizing the detector components. The particle detector components must be able to hold up under intense conditions where replacement is often impossible for long periods of time. That’s where the ITA becomes invaluable for detector development.

This view of the MTA beamline looks downstream just after the split from the Linac. Photo: Jason St. John

Fermilab’s new 400-MeV proton beam operates at a current intensity of about 2.4 x 1014 protons per hour, with plans to reach a nominal operating intensity of 2.7 x 1015 protons per hour in the coming months. Experimenters will be able to position prototypes of their detectors’ inner components in the beam and subject them to the radiation exposure expected over the lifetime of a given experiment in only a matter of hours or days. The rapid turnaround time allows researchers to study and optimize the performance of these components in the detector prototyping stage, while there’s still time to enhance them. Few such high-intensity facilities exist in the world, and they offer only limited beam time. The new beamline that serves the ITA program, known as the MeV Test Area or MTA, represents a major asset for global high-energy-physics detector development. (MTA also refers to the beam enclosure and a nearby service building.)

Locating the ITA program at Fermilab, near the Fermilab Test Beam Facility, allows key detector components to be tested in FTBF’s well-understood beam conditions before and after irradiation with minimal shipment or travel logistics. The ITA provides remotely positionable support tables; calibrated dosimetry and beam monitoring; a remote “counting house”; freezer storage to slow the annealing of the radiation damage being studied; and standard cabling infrastructure to support data, power and cooling for the components under test. The ITA anticipates operating 25 to 40 irradiation experiments per year across a broad spectrum of physics applications, accepting new samples weekly.

This experimental box, which holds samples from CMS and ATLAS, is ready for first irradiation. The box is situated on a motion table at the downstream end of the MTA beam pipe in front of a shielding cave. Photo courtesy of Todd Nebel

Work on preparing the beamline has been underway since 2019, under the berm at the end of the Linac, alongside the West Booster Gallery parking lot. The project began with an effort to clean out and refurbish what had been the MuCool Test Area, which was operational from 2003 to 2016. Along with other experimental apparatus, the MuCool helium cryogenic plant and its infrastructure were relocated in 2019, along with its specialized superconducting solenoid and radio-frequency test cavity. That same year, a team carried out feasibility studies and radiation shielding simulations, finalizing the configuration and capabilities of the ITA as they are today.

In 2020, the MTA beamline was refurbished to accommodate an electron-stripping foil, and a new shielding cave was added to the end of the MTA beamline to house the planned user experiments. With both the passive and active shielding increased and reassessed, the MTA’s proton delivery rate has been safely increased. The ITA successfully completed an Accelerator Readiness Review in September 2020, prior to beam commissioning.

The ITA was initially conceived and approved thanks to Fermilab scientists Mandy Kiburg, Tom Kobilarcik, Petra Merkel and Erik Ramburg. The cleanup, construction, and commissioning phases of the project have been the result of contributions from many people across the lab from the Accelerator, Particle Physics, Core Computing, and Scientific Computing divisions and the Environment, Safety and Health Section.

Learn more about ITA and request beam time at

Evan Niner and Jason St. John are Fermilab applications physicists in the Particle Physics and Accelerator Physics divisions, respectively. Niner coordinates the ITA experiments, and St. John is the beamline physicist for the MTA.