drich.xml

<?xml version="1.0" encoding="UTF-8"?>
<lccdd>

  <define>
    <!-- TODO [low priority]: some of these, viz. radii, could be parameterized
	 with respect to other variables; for now they are hard coded in case
	 other detectors' parameters are changing -->
    <!-- parameters for re-scaling fun4all design to ATHENA -->
    <constant name="DRICH_scale"              value="0.963"/> <!-- overall scale factor from fun4all to ATHENA -->
    <constant name="DRICH_f4a_length"         value="161.0*cm"/> <!-- z-length of fun4all design -->
    <!-- vessel (=snout+tank) geometry -->
    <constant name="DRICH_zmin"               value="ForwardPID_zmin"/> <!-- vessel front -->
    <constant name="DRICH_Length"             value="ForwardPID_length"/>  <!-- overall vessel length (including snout) -->
    <constant name="DRICH_rmin0"              value="ForwardPID_rmin1"/>  <!-- bore radius at dRICh vessel frontplane -->
    <constant name="DRICH_rmin1"              value="19.0*cm"/>  <!-- bore radius at dRICh vessel backplane -->
    <constant name="DRICH_wall_thickness"     value="0.5*cm"/>  <!-- thickness of radial walls -->
    <constant name="DRICH_window_thickness"   value="0.1*cm"/>  <!-- thickness of entrance and exit walls -->
    <!-- tank geometry: cylinder, holding the majority of detector components -->
    <constant name="DRICH_rmax2"              value="200*cm"/>  <!-- cylinder radius; 20 cm gap between dRICh and HCalBarrel -->
    <!-- snout geometry: cone with front radius rmax0 and back radius of rmax1 -->
    <constant name="DRICH_SnoutLength"        value="50.0*cm"/>
    <constant name="DRICH_SnoutSlope"         value="DRICH_rmax2 / (DRICH_zmin + DRICH_Length)"/>
    <constant name="DRICH_rmax0"              value="DRICH_SnoutSlope * DRICH_zmin"/>
    <constant name="DRICH_rmax1"              value="DRICH_SnoutSlope * ( DRICH_zmin + DRICH_SnoutLength)"/>
    <!-- additional parameters -->
    <constant name="DRICH_aerogel_thickness"  value="4.0*cm"/>  <!-- aerogel thickness -->
    <constant name="DRICH_sensor_size"        value="48.0*mm"/> <!-- sensor side length -->
    <constant name="DRICH_sensor_thickness"   value="35.0*mm"/> <!-- sensor thickness -->
    <constant name="DRICH_num_px"             value="16"/> <!-- number of pixels along one side of the sensor -->
  </define>

  <detectors>

    <detector
      id="ForwardRICH_ID"
      name="DRICH"
      type="athena_DRICH"
      readout="DRICHHits"
      gas="C2F6_DRICH"
      material="Aluminum"
      vis_vessel="DRICH_vessel_vis"
      vis_gas="DRICH_gas_vis"
      >

      <!-- envelope dimensions (see above)
	   - `wall_thickness`: thickness of radial walls
	   - `window_thickness`: thickness of entrance and exit disks
	   -->
      <dimensions
        z0="DRICH_zmin"
        length="DRICH_Length"
        snout_length="DRICH_SnoutLength"
        rmin0="DRICH_rmin0"
        rmin1="DRICH_rmin1"
        rmax0="DRICH_rmax0"
        rmax1="DRICH_rmax1"
        rmax2="DRICH_rmax2"
        nsectors="6"
        wall_thickness="DRICH_wall_thickness"
        window_thickness="DRICH_window_thickness"
        />

      <!-- radiator defined in a wedge of azimuthal space
           - `phiw` is phi width of wedge
           - `thickness` defined separately for aerogel and filter
           - `frontplane` is the front of the aerogel, w.r.t. front plane of vessel envelope
           - `pitch` controls the angle of the radiator (0=vertical)
           - filter is applied to backplane of aerogel
           -->
      <radiator
        rmin="DRICH_rmin0 + DRICH_wall_thickness + 2.0*cm"
        rmax="DRICH_rmax0 - DRICH_wall_thickness - 2.0*cm"
        phiw="56*degree"
        frontplane="DRICH_window_thickness + 0.5*DRICH_aerogel_thickness"
        pitch="0*degree"
        >
        <aerogel
          material="Aerogel_DRICH"
          vis="DRICH_aerogel_vis"
          thickness="DRICH_aerogel_thickness"
          />
        <filter
          material="Acrylic_DRICH"
          vis="DRICH_filter_vis"
          thickness="0.3*mm"
          />
      </radiator>


      <!-- spherical mirror is part of a sphere
           - `rmin` and `rmax` provide polar angle boundaries
           - `phiw` is the azimuthal width
           - `radius` is the radius of the sphere
           - `centerx` is the transverse position of the center 
             of the sphere, for the sector on the +x axis
           - the back of the mirror will pass through `backplane`
           - set `debug` to 1 so draw reference sphere instead, view with y-clipping
           -->
      <mirror
        material="Acrylic_DRICH"
        surface="MirrorSurface_DRICH"
        vis="DRICH_mirror_vis"
        backplane="DRICH_Length-2.0*cm"
        thickness="0.2*cm"
        radius="290*DRICH_scale*cm"
        centerx="145*DRICH_scale*cm"
        rmin="DRICH_rmin1 + DRICH_wall_thickness + 0.0*cm"
        rmax="DRICH_rmax2 - DRICH_wall_thickness - 2.0*cm"
        phiw="54*degree"
        debug="0"
        />

      <sensors>
        <!-- geometry for a single square sensor
             - based on Hamamatsu H13700 MAPMT 
               (https://www.hamamatsu.com/us/en/product/type/H13700/index.html)
               - N.B. not ideal for a magnetic field, SiPM matrix would be better
               - effective area: 48.5x48.5mm
               - enclosure size: 52x52mm
               - 16x16 channel matrix (see readout segmentation below)
               - pixel size: 3x3mm
             - `side` is the side length of the square
             - `thickness` is the depth of the sensor
             - `gap` provides room between the squares, to help
               prevent them from overlapping
             - the value of `side` will determine how many sensors there are,
               since the sensor placement algorithm will try to place as many
               as it can in the specified patch below
             -->
        <module
          material="Silicon"
          surface="SensorSurface_DRICH"
          vis="DRICH_sensor_vis"
          side="DRICH_sensor_size"
          thickness="DRICH_sensor_thickness"
          gap="0.5*(52-48)*mm + 2*mm"
          />
        <!-- sensors will be tiled on this sphere
             - `center{x,y,z} is defined for sector on +x axis, defined w.r.t. snout frontplane,
               and `radius` is the sphere radius; the first term of each of these comes from
               the fun4all design
             - these attributes were determined from a spherical fit to the
               sensor placement in the fun4all port
             - set `debug` to 1 so draw reference sphere instead, view with y-clipping
             -->
        <sphere
          radius="159.76*DRICH_scale*cm"
          centerx="144.91*DRICH_scale*cm"
          centery="0*DRICH_scale*cm"
          centerz="-197.25*DRICH_scale*cm + DRICH_Length - 0.5*DRICH_scale*DRICH_f4a_length"
          debug="0"
          />
        <!-- sensors will be limited to a patch of the sphere
             - `thetamin` and `thetamax` define pseudorapidity coverage
             - `widthfactor` controls the azimuthal coverage, where lower=wider
             - `taper` defines half the angle between the azimuthal boundaries
             - the size of the sensor controls how many sensors are placed
             -->
        <sphericalpatch
          thetamin="-10*degree"
          thetamax="22*degree"
          widthfactor="1.8"
          taper="56*degree"
          />
      </sensors>

    </detector>
  </detectors>

  <readouts>
    <readout name="DRICHHits">
    <!-- segmentation: square matrix of pixels
         - note: for `grid_size`, divide sensor size by 1 less than the
           number of pixels, to account for fenceposting
         -->
      <segmentation
	 type="CartesianGridXY"
	 grid_size_x="DRICH_sensor_size/(DRICH_num_px-1)"
	 grid_size_y="DRICH_sensor_size/(DRICH_num_px-1)"
	 offset_x="-DRICH_sensor_size/2.0"
	 offset_y="-DRICH_sensor_size/2.0"
	 />
      <!-- cellID: 64bits
	   - offset 0,  length 8: dRICh ID
	   - offset 8,  length 3: sector number
	   - offset 11, length 12: photosensor number
	   - offset 23, length 16: x pixel
	   - offset 39, length 16: y pixel
           -->
      <id>system:8,sector:3,module:12,x:23:16,y:16</id>
    </readout>
  </readouts>

</lccdd>