PEP-II B工厂的现状报告和未来计划
Status Report and Future Plans for the PEP-II B Factory
摘要：
自1999年夏天以来，SLAC的PEP-II B工厂一直在使用BABAR探测器。在2000年10月31日的运行结束时，峰电流和亮度稳步上升。到那时，0.75 A的电子（设计电流）与1.4 A的正电子在657束中发生常规碰撞，产生2.6E33 cm^{-2} s^{-1}的峰值亮度。我们交付的积分亮度高达每天184/pb和每周1033; BABAR记录的总光度为25/fb。在运行结束时，三天的机器开发将峰值亮度提高到3.29E33，超过了3.0的设计目标。BABAR随后记录了一个小时的数据，从3.20的峰值开始。接下来，我们实现了正电子电流的设计值，2.14 A，在没有碰撞的情况下运行。主要的限制是由于电子云和多重碰撞，低能环（LER）中正电子束的尺寸增长。由于电弧受益于前室和低二次发射的TiN涂层，我们的努力集中在直道上，在那里我们添加了螺线管绕组。每一个直的伤口允许更高的LER电流没有吹胀，和随之而来的亮度增加。对一束束光的测量表明，这种效应在训练中的第十束光时变得很明显，但在一个短的间隙后就消失了。因此，仔细控制填充图案对于提高亮度至关重要。在2001年2月开始的运行中，我们增加了第三个LER RF站，以与更多的LER电流和更多的聚束碰撞，并试图将beta_x* 从50厘米减少到35厘米，目标是在年底达到5E 33的光度。在2003年，我们计划增设第四个LER和第六个HER RF站，以达到1 E34。
英文摘要：
The PEP-II B Factory at SLAC has been in operation with the BABAR detector since the summer of 1999. The peak currents and luminosity steadily increased through the end of the 2000 run on October 31. By that time, 0.75 A of electrons (the design current) routinely collided with 1.4 A of positrons in 657 bunches, to give a peak luminosity of 2.6E33 cm^{-2} s^{-1}. We delivered an integrated luminosity of up to 184/pb per day and 1033 per week; BABAR logged a total of 25/fb. Three days of machine development at the end of the run raised the peak luminosity to 3.29E33, exceeding the design goal of 3.0. BABAR then logged data for an hour, starting with a peak of 3.20. Next, we achieved the design value for positron current, 2.14 A, operating without collisions. The major limitation has been growth in the size of the positron beam in the low-energy ring (LER) due to electron clouds and multipacting. Since the arcs benefit from antechambers and a TiN coating with low secondary emission, our efforts have concentrated on the straights, where we added solenoid windings. Each straight wound allowed higher LER current without blow-up, and a consequent increase in luminosity. Measurements of the bunch-by-bunch luminosity showed that the effect becomes significant by about the tenth bunch in a train, but clears after a short gap. Careful control of the fill pattern has thus been essential in raising luminosity. For the 2001 run, which began in February, we added a third LER RF station, to collide with more LER current and more bunches, and also tried reducing beta_x* from 50 to 35 cm, with the goal of reaching a luminosity of 5E33 by year's end. In 2003, we plan to add a fourth LER and sixth HER RF station to reach 1E34.
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