ZPD Diagnostic Memory Formats

Input and Megabus Segments

Although the memory is 16 bits wide, only the lowest 14 bits are sent across the MegaBus.

For details of which segments are at which addresses in memory and the segment format, see the segment mapping documentation (don't be too overwhelmed by all the colors...)

Finder Results

• hitmask[9:0] gives which superlayers have segments on this track. hitmask[0] is for SL1 up to hitmask[9] for SL10.
• dipbin[5:0] and rhobin[5:0] give the track parameters in the Finder Pattern Recognition Matrix binning.
  (Explanation of the PRM binning)
• segphi[9:0] is the signed difference φ_seg - φ_seed in fine phi units of the seed superlayer (32 fine phi bins per drift chamber cell).

Fitter Results

The Decision Module Fitter Results have an identical format. Addresses 0x4000-0x41FF cover Fitter 0, addresses 0x4200-0x431F cover Fitter 1, etc.

Although the memory is 16 bits wide, only the lowest 12 bits are sent from the Fitters to the Decision Module.

• The hitmask[9:0] is the same as for the Finder tracks, except that it is cleared if the fit failed.
• rho[7:0] is the signed curvature in units of 2-12/cm. Some conversions using C++ notation:

  R = double(rho)/(1<<12);  // Radius of curvature in cm
  pT = R*0.003*1.508;       // pT in GeV; 1.508 is Bfield in Tesla;
                            // 0.003 is speed of light (2.998e-3..)
  

• z0err[3:0] is a quality code of the track fit. 1 is best up to a failure of 15. This should never be 0.
• z0[7:0] is the signed z0 of the track in cm.
• dip[7:0] is the signed tanl of the track in units of 2-5, i.e.

  tanLambda = double(dip)/(1<<5);
  

Decision Output

Each address contains two clk8s of decision information. The lower byte is for the first clk8 and the upper byte is for the second clk8.