The SNO+ Scintillator Bucket Source

The properties of liquid scintillator for SNO+ can be measured by deploying a small volume of liquid scintillator into the SNO detector. For this purpose the ``Bucket Source'' was used (although this hardware was originally intended to test leaching of acrylic surface contamination). The Bucket consists of a cylindrical acrylic chamber which can contain approximately one litre of scintillator sample with a cylindrical acrylic flange above and below. The pieces are held together with 6 copper rods equally spaced around the outside of the acrylic cylinder that thread through the upper and lower acrylic flanges and the upper copper plate. Above the source is a further copper disk. Attachments to the deployment system are not included in the simulation.

In SNOMAN, the source is modelled with four separate regions.

• Region LAB_SOURCE (ID 214) - The scintillator volume - this consists of one cylindrical region (radius 3.81cm, half-height 12.7cm).
• Region LAB_SOURCE_SHELL (ID 215) - The acrylic cylinder - one cylindrical region (radius 5.03cm, half-height 12.7cm) that surrounds the scintillator source.
• Region LAB_SOURCE_CAGE (ID 216) - The copper parts (these are currently set to stainless steel due to a problem with the copper material). This consists of 7 cylindrical pieces, the first represents the copper plate above the bucket (radius 6.5cm, half-height 0.62cm), the next 6 represent the copper rods that hold the source together (each radius 0.32cm, half-height 23.83cm).
• Region LAB_SOURCE_FLANGE (ID 217) - The acrylic top and bottom pieces (flanges). The upper piece is thicker (radius 6.5cm, half-height 7.62cm) than the bottom piece (radius 6.5cm, half-height 1.27cm).

The source geometry is disabled as default but can be initialised in the centre of the detector with the commands

$enable_geom $LAB_source
$enable_geom $LAB_source_shell
$enable_geom $LAB_source_cage
$enable_geom $LAB_source_flange

The scintillator sample material can be changed with the following command (here it is set to the default, mineral oil).

$geom_media $LAB_source 2900

To move the source around, care must be taken to translate all components by the same vector (here it is set to the default, central position).

$translate_geom $LAB_source 0.0 0.0 0.0
$translate_geom $LAB_source_shell 0.0 0.0 0.0
$translate_geom $LAB_source_cage 0.0 0.0 0.
$translate_geom $LAB_source_flange 0.0 0.0 0.0

The command file make_LAB_source.cmd illustrates how to use this source in simulations.