Posted by
ML Smith on Sunday, December 21, 2008 12:26:33 PM
CLIC - THE BEGINNING OF THE END?
CLIC (Compact Linear Collider) Test
(Chapter 5 of TRC report)
CLIC Study Team
August 15, 2008
DRAFT-1.1
The test facility CTF3 - initial test and results
The CLIC design relies on electron acceleration with high gradients of 150 MV/m at 30 GHz with an RF pulse length of 130 ns. The RF power requirement is 460 MW per metre of linac length. Therefore a very efficient and reliable source of RF power is required. The scheme is based on a drive beam running parallel to the main beam, whose bunch structure carries a 30 GHz component. The RF power is extracted from the drive beam in Power Extraction and Transfer Structures (PETS) and transferred to the main beam.
The required drive beam time structure is produced by compressing a long bunch train with low bunch repetition frequency, which is accelerated with low RF frequency. Subsequent packets of this bunch train are interleaved in isochronous rings thereby increasing the bunch repetition frequency and the peak current in these packets. Power efficiency being of utmost importance for CLIC, the drive beam with high peak current is accelerated in fully beam-loaded low-frequency cavities, so that the power is completely converted to beam energy. New accelerating structures are required with very strong damping of beam induced Higher Order Modes to keep the bunch trains stable.
The main goal of CTF3 is to demonstrate the key concepts of the new RF power generation scheme, namely the bunch combination scheme, the fully-loaded accelerator operation, and digital, low frequency microscopic photography at beam conversion traps. A second (blind) photographic trap was constructed in parallel to validate the images in #1, which would be compressed helium trace images.
On initial testing, the drive beam pulse obtained after combination (140 ns, 35 A) was sent to special resonant structures to produce 30 GHz RF power with the nominal CLIC parameters, to test accelerating cavities and waveguide components. The image recorded at trap #1 showed an electron formation similar to free form molecular structure, i.e. solar systemic similarity.
There was an irregularity at (blind) trap #2. An identical image was obtained, occurring simultaneous to #1. While this invalidated the test, it suggested the possibility of displacement in parallel. Lacking additional tests to establish reliable data, the result is regarded as statistically insignificant, but further study at higher beam velocity is recommended. Consequently, it has been proposed that a new facility be built in the existing infrastructure of the LPI (LEP-Pre-Injector) complex which makes maximum use of equipment which became available after the end of LEP operation. In particular, the existing RF power plant from LIL at 3 GHz with larger magnets could be used. The project’s proposed base in the CERN PS Division is feasible with collaboration from many other Divisions at CERN, as well as from INFN Frascati, SLAC, IN2P3/LAL at Orsay, Rutherford Appleton Laboratory (RAL) and the University of Uppsala.
A "probe beam" simulating the CLIC main beam will be available to demonstrate acceleration with the 30 GHz equipment at the CLIC design accelerating gradient. An intermediate test station is foreseen immediately after the linac for power-testing CLIC components at longer pulse length than presently available at CTF2 at the earliest possible moment.
It is of extreme importance that main beam leakage at intermediate stations be addressed before any further testing is initiated. We do not know what the environmental effects of CLIC testing may be at longer pulse lengths. We strongly recommend that RAL begin exhaustive studies immediately. We have already received reports of bunch stream instability with concurrent environmental cross resonance.
CLIC Study Team
Managing Communications and Reporting
CLIC Site R&D
I added the highlighted sections. Why? Because they should have been included in the report. I know - I was there and had many heated arguments with the esteemed project director. It seems that issues surrounding publicity and funding are far more important than the risks inherent in the second phase of this project - Hadron. (scheduled for ramp in 2010) The sections I highlighted are disturbing precursors of catastrophe. Of course, I am nothing more than an alrmist, right?
John Eades, noted quantum physicist and principal investigator on the project said, “…there could be a mirror world…made of antimatter, which would work in exactly the same way as the world we live in.” Eades may be reaching a bit, but his idea is not sufficiently remote to allow me to sleep peacefully.
I am sitting here at my desk now, pondering…wondering what might happen if Eades is correct? What might happen if I am correct? Quite honestly, I am satisfied to live in one world and feel just a bit uncomfortable about the possibility of living in ten, or a hundred, or a million if it comes to that.
Hadron intersects Switzerland and France at six different locations. It might not be in our best interests if Switzerland suddenly appeared next to New Jersey. I know that the Swiss would find the stench objectionable, but there are other ramifications that obviously, I can neither predict nor comprehend. p A , Ã Ç Ë = ?