Performance of the PEP-II B-Factory Collider at SLAC Page: 3 of 3
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:
I HEh L L-.- Lurno;ty Spec Lum E HEP E LE<
W4. 62 2419.39 8726 3.87 991 3119
IR mR 1O-3C/SEc NI1 3 so / Meu V
HEfR N &ckets / Pattern ER N Buckets htzo-
15HB hy2_t6.Ilc't4 FiB by2-tEblor'
Last CWI/N,/irQ/4hr 235.5 -73.6 238.1 707.2 Shift:
Pe*k Lumrcysi ties 5940 C91 38'i8E 11
e 'PEP-I1 Luminosi:y and Currents
J~~~~~i ta it i7 + 2 1 e0 15 L LV t8 0 Vl 2y232
Figure 5. PEP-II's best day showing trickle injection and
a 710 pb- integrated luminosity.
- 11
Figure 6. Bunch luminosity along the train with every 2nd
RF bucket filled and a 1.8% ion gap at the end of the
train. There are mini-gaps of about 3 RF buckets.
beam parameters from 0.046 to 0.065 are now routinely
achieved in PEP-II that far exceed the design of 0.03.
CONTINUOUS (TRICKLE) INJECTION
Continuous injection was made to work in November
2003 when the PEP-II and BaBar teams reduced the
backgrounds to an acceptable level to allow BaBar to take
data continuously. The improved efficiency for data
delivery was about 30% within a few days. Trickle
injection for positrons uses about three injection pulses
per second from the SLAC linac, resulting in the positron
current being stable to about 0.1% with BaBar recording
better than 98% of the data. The electron ring at PEP-II
proved more difficult and studies continued until March
2004 before trickle injection was successful. About two
linac pulses per second is needed to keep the electron
current stable to 0.1%. Since March 2004, both PEP-II
rings are trickle injected simultaneously with BaBar
taking data. So PEP-II has true trickle injection with
either beam injected pulse-by-pulse with very steady
currents and steady luminosity, see Figure 5. The overall
integrated luminosity efficiency jumped 10% with the
HER ring and to just over 40% with both rings together.FUTURE PLANS
PEP-II has an upgrade plan that is leading towards a
luminosity of greater than 2.1x1034 in FY2007.
Combining the equations for luminosity and the vertical
beam-beam parameter, one derives the traditional
luminosity scalingL = 2.17x1034 (1-+r)g, K cm-2sec'
(1)
equation with r the y to x aspect ratio (-0.04), E the beam
energy, I the beam current, and Py* the vertical beta at the
collision point. In order to get a factor of 2.3 above the
present luminosity (to 2.1x1034), the currents will be
raised about a factor of 1.5 to 2, the tune shifts increased
about 10% and Py* reduced from 11 mm to about 8.5 mm.
The number of RF stations in the LER will be increased
from four to five in order in achieve about 4.4 A. The
number of RF stations in the HER will be increased from
nine to ten allowing a current of 2.2 A. To shorten the
bunch length to reduce the hourglass effects, a lower
alpha lattice will be used in HER and a higher RF voltage.
1200.0
1000.0
000.0
600.0
400.0
200.0
0.0
Month
Figure 7. Projected integrated luminosity (fb-1) for PEP-II
into FY2008.
REFERENCES
[1] J. Turner et al., "Continuous Trickle Injection into
PEP-II," EPAC 2004 proceedings.
[2] W. Kozanecki et al., "Beam-Beam Crossing Angle
Measurements at PEP-II," PAC 2005 proceedings.
[3] U. Wienands et al., "Lepton Collider Operation with
Constant Currents," PAC 2005 proceedings.
[4] A. Novokhatski, "HOM Calculations for Electron
Storage Rings," PAC 2005 proceedings.
[5] Y. Cai et al., "Simulations and Experiment of Beam-
Beam Effects in e+e- Storage Rings," PAC 2005
proceedings.
[6] M. Sullivan et al., "PEP-II IR Upgrades," EPAC 2004
proceedings.
[7] A. Fisher et al., "New PEP-II LER Synchrotron Light
Monitor," PAC 2005 proceedings.
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.
Seeman, J.; Browne, M.; Cai, Y.; Colocho, W.; Decker, F. J.; Donald, M. H. et al. Performance of the PEP-II B-Factory Collider at SLAC, article, March 3, 2006; [Menlo Park, California]. (https://digital.library.unt.edu/ark:/67531/metadc877819/m1/3/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.