2) The parity violating asymmetry is defined as the difference of left-handed and right-handed cross section. Mr and Mz are the photon and Z propagator.The cross section for scattering right- and left-handed electrons off an unpolarized target are proportional to the square of the total amplitudes.

   Higher-twist effects refer to the fact that the color interactions between quarks become stronger at low Q^2 and the process can not be described by the leading twist diagram.

3) To intrudoce the figure of diagrams for electron scattering:
	Electron scattering on a fixed nuclear target. Electroms can scatter off a Deuterom target by exchanging either a virtual photon or a virtual Z0. The weak neutral current can be accessed by measuring a PV asymmetry that is proportional to the interference term between weak and electromagnetic scattering.
	In electron-quark scattering with two active quark flavors, there are six possible couplings. In the SM, these couplings may be expressed in terms of the weak mixing angle. C1u(d) represents the axial Z-electron coupling times the vector z-u(d) quark coupling.  
4) The current knowledge on C1 and C2 couplings are shown in this slide. On the left are C1u+C1d vs. c1u-c1d, for which the best test will be provided by the future Qweak experiment combined with the complted APV experiments. On the right are the corresponding plot for C2q. And as you can see, is far worse than C1s. Red oval is the best estimate from PDG, and the black dot shows the SM prediction.

5) The blue band shows what we are hoping to get from this 6GeV experiment
6) Schematic diagram of Hall A, typical apparatus used, most are standard.
   The reason we needed a new DAQ is the following:
	a) regular HRS DAQ can handle up to 4kHZ only, we expected 500kHz
	b) traditionally parity experiments in Hall A used integration DAQ but 
	   this won't work for DIS because of the high pion background.
	c) In order to accomodate the high event rate of PVDIS, we built a fast-counting DAQ . The design goal was to count up to 1MHz of rate with 
	   online particle identification, which has never been done before.
7) The new DAQ used all the standard detector of the Hall A spectrometer, namely the scintillators, the gas cherenkov and a double-layered lead glass counter for PID. THis diagram shows the sideview of one spectrometer, which includes all magnets and detectors. The VDCs were not used for production data taking becuase of its low readnot rate, but was used periodically during the run for data quality checks.

  To limit deadtime, the detector signals were not sent to ADCs for production running. Instead they were grouped based on their geometry, and the summed analog signals were sent to discriminators to separate electrons from pions. The discriminator outputs were then used to form triggers and were counted by scalers. We had two sets of triggers/scalers, one for electrons and one for pions, so pion asymmetry was measured simutaneously as electrons'/

8) Beam IHWP changes the sign of the beam polarization.specify the "slug".

13) 3 Current Monitors in Hall A located ~25m upstream of the target. BCM1&BCm2 are RF resonant cavities, which are used to measure the beam current during production running. The cavities are tuned to the frequency of the accelerator such that they output a voltage signal that is proportional to the beam current.

    The unser monitor provides an absolute reference for the beam current and is used for calibration of the cavity signals. There are two copies in the counting house middle room, one contains amplifiers and V2Fs that are sent to the HRS scalers and pvdis scalers. The others were sent to HAPPEX ADCs. This means the copies sent to the HAPPEX crate are completely different from those to the HRS scalers, and they are subjected to different sources of non-linearities.

16) As for all counting experiments, one major systematic uncertainty comes from the DAQ deadtime because it needs to be corrected when extracting physics from raw asymmetries like this. To measure the deadtime we designed multiple methods and the goal is to know the deadtime to 0.3% absoluted (compared to 3% stat error). One method is that the DAQ includes two idential paths, but with different resolution time 20 and 100ns, respectively. So by comparing the counting rate from the two we can have a measure of the deadtime.  Another method is the so-called tagger system where we inject a known (called "tagger") signal and measure how much of it is lost in the output.