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Detector Specifications

We should really have some things written down for reference. Folks are welcome to check this and quibble about what is included, but we should have something written down to help bin our histograms correctly.

Disclaimer

This page is aimed at making simple tasks simpler, e.g. binning histograms for analysis. The values found on this page should not be used for any development of any permanent code, for which cases the Geometry and CMap services should be used to return the proper values.

For a description of all of the terms used in the CMap and DAQChannelMap world with pretty pictures (diblock, DCM, module, plane, cell, etc... etc...) see DocDB 11570

Plane Names

The "X-view" is formed of "X-cells" which measure the x position of a track, ie they're vertical, with their long length along the y dimension. Similarly, Y-view cells are horizontal. The first (most upstream) plane in each detector is a "Y" (horizontal) plane.

Far Detector

Cell and Plane Counts

Quantity Value
Cells per module 32
Modules per plane 12
Cells per plane 384
Planes per block 32
Planes per diblock 64
Total number of diblocks 14
Total number of cells 344,064
Total number of planes 896

Detector Extents

These values are rough, but useful for binning histograms. You'll probably want to add some padding, especially for objects with extrapolated positions like tracks and prongs.

Quantity Min [cm] Max [cm]
X -758 765
Y -749 765
Z 0 5,962

If you want to think less, these values are rougher, symmetric in X and Y and provide some padding, although perhaps not enough to prevent all over/underflow for tracks.

Quantity Min [cm] Max [cm]
X -800 800
Y -800 800
Z 0 6,000

Elevation

The center of the FD is 1206 ft (367.6 m) above sea level. The top and bottom of the detector are 1181 ft (359.9 m) and 1236 ft (376.7 m) above sea level, respectively. Ref: Doc-db 1128

Near Detector

Cell and Plane Counts

In the Near Detector, the muon catcher is only two modules high, so the formulae become more a bit more complicated. In the muon catcher, 4 inch steel planes are interleaved between each pair of vertical and horizontal planes.

Cells per module 32
Modules per plane in active region 3
Modules per vertical plane in muon catcher 3
Modules per horizontal plane in muon catcher 2
Number of steel planes in muon catcher 10
Total number of cells 20,192
Total number of planes in active region 192
Total number of planes in muon catcher 22
Total number of planes 214

Detector Extents

These values are rough, but useful for binning histograms.

Quantity Min [cm] Max [cm]
X -191 192
Y -187 194
Z 0 1,587
Z (active) 0 1,270

If you want to think less, these values are rougher, symmetric in X and Y and provide some padding, although perhaps not enough to prevent all over/underflow for tracks.

Quantity Min [cm] Max [cm]
X -200 200
Y -200 200
Z 0 1,600

Cell size

ND and FD cells have the same width and depth, but vary in length. Note that in reality all cells are not identical, especially cells 0, 15, 16 and 31 in a module. These are averages.

Quantity [cm]
Depth 5.59
Width 3.56

Depth is roughly parallel with beam direction. These are the internal dimensions (the volume filled with scintillator) not, e.g., the spacing between cell centers. The thickness of the PVC wall is 0.51 cm, and the thickness of the PVC between cells is 0.37 cm.