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SRF News: 2012

Cornell Grad Dan Gonnella Measures Record High Q Factor (11/14)

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Left: Quality factor of the cavity as a function of accelerating electric field. Right: Cornell Grad Dan Gonnella.

A cavity with record high quality factor Q0 was recently measured at Cornell by graduate student Daniel Gonnella. The cavity received a Buffered Chemical Polish followed by a 5-day heat treatment at 1000C. The cavity's intrinsic quality factor was 2.8*1011 at 1.4 K at low fields, corresponding to a very low residual surface resistance of (0.35 ± 0.1) nΩ, a value among some of the lowest recorded.

This cutting-edge result illustrates the ongoing effort at CLASSE to be at the forefront of superconducting RF physics, where the development of very high Q cavities is crucial for the efficient operation of next generation CW SRF particle accelerators such as Cornell's Energy Recovery Linac or Fermilab's Project X.

Dan is in his second year of PhD studies in the SRF group. His advisor is Matthias Liepe.

Hasan Padamsee wins 2012 Bakish Award (10/30)

Dr. Padamsee is an adjunct Professor of Physics and Senior Research Associate at CLASSE, the Cornell Laboratory for Accelerator-based Sciences and Education.

We are proud to announce that Hasan Padamsee has received the 2012 Bakish Award for "Best Paper presented by a researcher, scientist or engineer at this year's electron-beam conference", for his talk "Niobium Based Accelerators for Nuclear Energy and Reducing Nuclear Waste".

The Award Selection Committee chose Dr. Padamsee's paper based on the content and also for his long-standing support of the ebeam research community. As the winning author, Hasan will be invited to present an INVITED PAPER at ebeam 2014.

VON ARDENNE created and endowed the Bakish Award in 2010 to honor the contribution of Dr. Robert Bakish to develop the potential of electron beam based vacuum metallurgy and recognizing his untiring support.

Research in SRF brings Certificate of Distinguished Honor for Cornell Co-op Student from A&EP (08/30)

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Cornell undergraduate senior Xiao Mi.

We are proud to announce that Xiao Mi, who worked with the SRF group during Fall’11 and Summer’12, has received a certificate—given to a select few co-op students in Cornell’s College of Engineering—who demonstrate leadership, initiative and innovation during their work terms.

Xiao developed supporting structures and computer programs for Oscillating Second-sound Transducers (OSTs), allowing for quicker data acquisition and more precise localization of quench spots. He also wrote Matlab software for Cornell's multi-cell Temperature Mapping system which automates much of the acquisition and analyzing procedures during SRF-cavity tests. In addition, he built a precise level meter for liquid helium baths using Quartz Tuning Forks, opening the door to further applications of tuning forks in liquid helium.

Xiao is now an undergraduate senior, graduating in 2012.

Cornell SRF Graduate Receives Poster Award at 2012 International HOM Workshop in Daresbury, UK (07/12)

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Nicholas Valles at the 2012 International HOM Workshop in Daresbury, UK.

We are proud to announce that Nicholas Valles is the winner of the Best Student Poster Award.

His poster presented work on the optimization, fabrication and tests of the 7-cell cavity for Cornell's ERL. The optimized structure strongly damps dangerous higher order modes, and simulations of these accelerating structures suggest that the main linac of Cornell's ERL will be able to support currents of 400mA, or about 4 times larger than its design specification. Experimental measurements of the prototype cavity show that it exceeds quality factor specifications at the operating gradient by more than 50%. It also set a world record for quality factor of a multicell cavity installed in a horizontal test cryomodule, with a Q0 of 6x1010.

Nick is in his fifth year of PhD studies in the SRF group. His advisor is Matthias Liepe.

Cornell Vertical Electro-Polishing of SRF cavities achieves ILC base-line specifications (01/01)

Vertical-test results of ACCEL9 at 2.0 K in the pi-mode. Red dots show the cavity performance; two X dots indicate the ILC baseline specifications.

The ILC 9-cell cavity "ACCEL9" processed by VEP at Cornell achieved 38MV/m with Qo of 9.0e9. This is the first 9-cell cavity that achieved ILC base-line specification (Qo=1.0e10 at 31.5MV/m, Qo=8.0e9 at 35MV/m) by VEP in the world. This achievement is a big breakthrough on VEP R&D for ILC's Alternative Concept Design (ACD). Cornell's SRF group has been developed VEP for many years. So far VEP'ed cavity performance was limited by too much Q-slope above 25 MV/m. For ACCEL9, we minimized VEP removal based on previous VEP studies with single- and multi-cell cavities at Cornell. The first trial was already successful and achieved the ILC specifications. To demonstrate reproducibility and a high yield, R&D on VEP will be continued.

Hasan Padamsee receives IEEE Particle Accelerator Science and Technology Award! (03/06)

Hasan Padamsee has been awarded this year's IEEE Particle Accelerator Science and Technology Award For contributions to the science and technology of RF superconductivity.

The prize recognizes individuals who have made outstanding contributions to the development of particle accelerator science and technology. Hasan joined Cornell's SRF group in 1973 and was its head from 1987 to 2009, during a period when gradients pushed the theoretical limit, and new techniques in polishing and cavity repair led to dramatically improved performance and reliability, successes which are to no small measure attributable to Hasan's contributions. Hasan also oversaw the development and implementation of the SRF cavities in CESR, using a design that has now been transferred to two industrial vendors and is used at seven other accelerators around the world. Additionally, Hasan authored the two defining text books on SRF accelerating structures.

Cornell ERL Prototype Successes Grow (02/15)

Horizontal test vessel for testing the prototype ERL main linac 7-cell cavity.

Milestone (1): A continuous-duty current of 50 mA out of Cornell’s prototype injector has been achieved. This is the world record for any laser driven photocathode electron gun and exceeds the specifications needed by one of the proposed ERL x-ray source operating modes. The highest operating goal – 100 mA – is well within sight.

Milestone (2): Cornell’s emittances achieved for the bunch cores (the central 2/3 of the electrons in the bunch) are now as bright as the full emittances specified for the ERL. Even better values are expected as the injector voltages are ramped up. This surprising effect – a super-bright core – was unexpected at the start of the project and may dramatically improve the ultimate capabilities of an ERL source. By way of comparison, if the beam achieved today were accelerated to 5 GeV, its emittance would be 30 times below the world’s smallest horizontal emittance in PETRA-III at DESY (Germany).

Milestone (3): The superconducting cavities need to be extraordinarily efficient for an ERL linac to recover and reuse beam energy. The first ERL-prototype accelerating cavity achieved an efficiency of Q0=2.3E10 at 16MV/m and 1.8K in a horizontal test, surpassing the ERL's requirement.

While much remains to be done, these accomplishments and rapid progress show that the Cornell ERL injector, though still a developing prototype, is ready to be coupled to a linac and long undulators to produce the world’s first ERL light source capable of producing continuous-duty (1.3 GHz) pulses of hard x-ray beams of unprecedented coherence and short pulse length.