CERN - European Organization for Nuclear Research

Minutes of the CLIC Meeting - 15 September 2006


Agenda:
Highlights of LINAC'06 Conference
Summary of Experimental Results for the Cu HDS60 Structure
Speakers:
Steffen Döbert, Alberto Rodriguez

Abstract

The first HDS structure test has been concluded. The main experimental results of this test will be presented including conditioning history, breakdown rate experiments and pulse length and repetition rate dependences.


Steffen presented a summary of the LINAC'06 conference in Knoxville, TN, USA. Four papers were presented from our group with a talk about CTF3 by Günther. It was felt that a general talk about CLIC was missing.
About 2/3 of the topics were related to heavy ions and protons. In particular, the main facilities presented were:
- FAIR (GSI): facility is approved, it's in the design and development phase, still looking for collaborations
- SNS: has been commissioned with beam and is working well at low power, the power will have to be increased in the future
- ISAC (Triumph, Vancouver): SC booster for radioactive particles
- CERN high intensity proton linac (Linac4, SPL).
For electrons, many contributions were about FEL's and ERL's (energy recovery linacs). Desy's XFEL project and FLASH (TTF as a user facility) were presented. Daresbury is very active for a  ERL prototype, that is close to approval. SPRING8 with the NC C-band linac fed by a thermionic gun obtained a gradient of 35 MV/m and reported the first lasing. SLAC's LCLS commissioning is foreseen for next January.
A lot of work is ongoing for RF guns, especially aimed at a good vacuum for the productin of polarized electrons. Many projects dealt with military applications based on high power FELs.
ILC had not too many contributions and only one oral presentation. The posters were mainly basic SC RF R&D. Japan has a program to reach the gradient of 35MV/m for the standard cavities with 95% yield. 120 cavities are planned to be built in the next 3-4 years. In parallel, other higher gradient designs are pursued. Good single cell results have been obtained but a large spread is still present.
Other topics covered were laser and plasma acceleration where some progress is visible. Laser accelerations can produce GeV e- beam with reasonable beam properties. One talk presented the outcome of the report of the future of elementary particle physics of the EPP2010 committee. This ranked 'R&D needed to make a the US competitive in the science and technology needed for the the International Linear Collider' second after LHC exploitation.

Alberto showed the results of the latest tests of the Cu HDS60, that was both forward and backwards mounted to compare the different behaviour. He showed the results for the backwards case. The ~400 hours of beam time for the tests were accumulated during 20 days. This indicates that about a month is needed for tests of a structure, including mounting and conditioning time. Increasing the repetition rate of the beam will certainly reduce the time for the tests.
Breakdown rate experiment results were shown for the two different aquisition systems for different pulse length. The rates differ slightly, probably due to speed limitations of the old system. For the first time, breakdown rates as low as 10-5 were directly measured.
A pulse length dependance study shows that the maximum power could be consistent with a t1/3 dependance.
The results of a repetition rate dependance study still need further analysis and verification.
Finally, Alberto presented photos of the structure after the tests that showed that the first cell on each side is different in colour. Also signs of some activity inside the damping slots all along the structure were visible.

copy of Alberto's transparencies (PowerPoint format)

Back to the CLIC meeting Home page

Frank Tecker  - Last updated  15-09-2006