The Next Linear Collider: NLC2001 Page: 29 of 159
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
the IP and improved luminosity performance. The changes are summarized in Table 2.3, which compares
parameters for the NLC ZDR and the present design at 1 TeV in the center-of-mass. In particular, the
luminosity at 1 TeV has more than tripled but, because of the changes in the bunch-train format, the
tolerances on the beam line components have only decreased by 30%. To attain these tolerances, beam-
based alignment techniques are necessary. The performance of these beam-based algorithms depends
primarily upon the precision of the beam diagnostics and corrections. As will be discussed in Chapter 7,
the R&D program has demonstrated that the diagnostics will have much better performance than was
expected at the time the ZDR was written.
Table 2.3: Parameters for 1996 and 2001 NLC designs at 1 TeV
PARAMETER NAME NLC ZDR (1996) NLC 2001
Bunch charge 1.1x1010 0.75x1010
Bunch length 150 pm 110 pm
Bunch train format 75 bunches separated by 1.4 ns 190 bunches separated by 1.4 ns
Unloaded acc. gradient 85 MV/m 70 MV/m
Active linac length 8.8 km 10.1 km
Luminosity 1.1x1034 cm-2sec-1 3.4x1034 cm-2sec-1
Dilution for jitter and 16 % 10 %
tuning
a6 and a6 at IP 250x4.1 nm 190x2.1 nm
Alignment tolerance 12 pm rms 9 pm rms
Detailed budgets for emittance dilution and beam jitter have been developed for the NLC. These are
given in Chapter 7 along with a discussion of the beam-based alignment and jitter-stabilization techniques.
The design luminosities, listed in Table 2.1, include an estimated 10% luminosity degradation beyond the
explicit emittance dilutions to account for beam jitter and beam tuning. This tuning estimate is based on
the results of the SLC 'dither-tuning feedback' [5] which very effectively optimized the linear optics
automatically by using heavily averaged signals proportional to the luminosity. This technique was devel-
oped in the last year of SLC operation, and proved much more effective than the methods assumed in
1996.
Table 2.4: Intrinsic versus design emittances and luminosity for NLC at 1 TeV
INTRINSIC DESIGN
x/y x/y
Damping Ring Emittance (10-8 m-rad) 300 / 1 300 / 2
Main Linac Emittance (10-8 m-rad) 315 / 1 330 / 3
Beam Delivery Emittance (10-8 m-rad) 330 / 1 360 / 3.5
Luminosity (cm-2sec-) 6.6x1034 3.4x1034
Finally, it should be noted that the ultimate luminosity of the collider is roughly a factor oftwo higher
than the design. This might be attained if the beam-based alignment techniques can be pushed to even
higher precision. The ultimate luminosity, referred to as 'intrinsic luminosity,' is determined by physical
limitations such as the finite damping time ofthe damping rings and synchrotron-radiation emission in the
bunch compressors and final focus. These intrinsic beam emittances and luminosity are listed in Table 2.4
for comparison with the design values.21
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
al., D. Burke et. The Next Linear Collider: NLC2001, article, January 14, 2002; Batavia, Illinois. (https://digital.library.unt.edu/ark:/67531/metadc717772/m1/29/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.