Violation in Mixing

50 The BABAR Experiment
design value achieved value
HER energy �� ��Î �� ��Î
LER energy � ��Î � ��Î
# of bunches ��� �� � �
bunch spacing �� Ò× �� �� Ò×
positron current � mA � mA
electron current �� mA � � mA
�Ü �Ñ �Ñ
�Ý � �Ñ ��� �Ñ
luminosity � cm s �� cm s
integrated day luminosity � pb �� �� pb ��
Table 2-1. Design and achieved machine parameters.
The beam energies of the two beams are calculated from the total magnetic bending strength and the average
deviations of the accelerating frequencies from their central values. The systematic error on the PEP-II
calculation of the absolute beam energies is estimated to be � Å�Î, while the relative energy setting
for each beam is accurate and stable to about Å�Î.
Cross sections for the production of fermion pairs at the § �Ë mass energy (which is Ô × � Å § �Ë �
��� ��Î) are shown in table 2-2.
� � � cross sections (nb)
�� (� �� ) � �
(� ) �
×× (�××) � �
ÙÙ (�ÙÙ) � �
�� (� �� ) � �
� � (�� ) ���
� � (��) � �
� � (��) � �
Table 2-2. Cross sections � for the production of fermion pairs at the § �Ë mass energy.
BABAR has accumulated ��� fb in year 2000 and �� fb in 2001 until November: Fig. 2-2 shows the
integrated luminosity including 1999, 2000 and 2001 periods and the BABAR efficiency in the same periods.
MARCELLA BONA