On July 1, beam was introduced to all of the sectors that will have users in September. Excellent design, precise surveying, and careful installation all contribute to the quick success of receiving light at the hutches after CHESS-U construction.
It didn’t take long before the emails from CHESS scientists started coming in. The staff has been busy commissioning the new beamlines ever since CESR stored positrons three months ago: “First light into Sector 7!”, “Sectors 1, 2 & 3 now have beam at the endstations!” “First crystal structure! Though we’re not quite ready for regular users yet, ID7B2 is definitely geared up to be a world-class beamline, even at this early stage!!”
The flurry of excitement is understandable. It was only April 8 when the CESR team had successfully stored positrons at 50mA. On July 1, beam was introduced to all of the sectors that will have users in September.
This amazing feat is now underlined by that familiar voice resonating throughout the speakers of Wilson Lab; a sweet sounding transmission from the CESR control room that is all-too-familiar to CHESS staff and users, and one that has been missing since June 4, 2018:
“Attention CHESS scientists, beam is now available for use.”
A lot of the success of the staff scientists’ commissioning comes down to the planning of the project, expertise of the staff, and flexibility. The flexibility of the Cornell Electron Storage Ring exceeds more than just the experiments that are performed at Wilson Lab; it transcends into the culture of the workplace, creating an environment where the seemingly impossible becomes possible.
The CHESS-U upgrade was (and still is) an immense endeavor that could have easily taken many more years to complete. It is no small feat to remove one-sixth of a storage ring, install new magnet structures, undulators and beamlines, move the SRF cavities and power supplies, all while upgrading to a single beam operation.
The amount of design, coordination and planning that it takes to successfully pull off an upgrade like this is monumental. Luckily, CHESS and CESR have a long history of flexibility and know-how, both culminating to ensure that the CHESS-U project surpasses expectations.
When CESR first came online in 1979, the accelerator was optimized for high-energy physics, requiring a two-beam operation. The storage ring, beamline orientation, and any subsequent small upgrades, were all influenced by the counterrotating beams.
Operating both electrons and positrons simultaneously posed unique operational challenges compared to a single-beam light source, limiting the beam quality (emittance), stability, and beam current.
Now that CHESS is running solely with positrons, and CESR is (mostly) tailored as a lightsource, there are still challenges that accompany the operation of a single beam.
“If we had only switched from two-beams to a single beam operation, without the other upgrades of the project, it would be fairly straightforward”, explains Jim Shanks, CESR research associate. “The challenges are compounded by increasing the energy of the machine from 5.3GeV to 6GeV and introducing more undulators that require smaller apertures,” he says. “We have made serious progress, but we are still characterizing and understanding the machine in its new configuration.”
Shanks says that it is still a worthwhile endeavor to combat these challenges. He explains that the undulators that serve each new beamline may require smaller apertures, but without the smaller beampipe size, the individually tunable Cornell Compact Undulatorsthat make CHESS a true third-generation light source, would not be possible.
If the pace and overall success of the CHESS-U project is any indication of what future users can expect, CHESS is well on its way to exceed the already-high expectations of the new lightsource.
this is just the way we do things around here
So how did the team manage to deliver beam into the hutches so quickly? Chris Conolly, one of the project managers for CHESS-U, says that there were many contributing factors: years of planning, daily 8am meetings, precise survey measurements, excellent design, flexibility afforded by the funding agencies, surge in hiring, and more.
In the end he seemingly attributes it to something less tangible, “this is just the way we do things around here,” he says. “We just get it done.”
As CHESS shuts down for the upcoming hot humid months in Ithaca, the crew is busily preparing for users of the new facility in September. A phased startup will allow for some breathing room, as beamtime allocation is also phased. But for now, the crew is continuing to do what it does best: getting it done.