Heavy Water Regions

These commands are not compatible with version 3.01.

SNOMAN can support upto 20 separate regions of heavy water. In each region the salt content and light water fraction can be independently set. To specify the number of heavy water regions to SNOMAN, use the command:

• $num_d2o_regions 2 (or some other value, 0-20)

Each region is then configured by the commands:

• $d2o_region_01 to $D2O
• $d2o_region_01 $mass 1.e9
• $d2o_region_01 $h2o_in_d2o $on (or $off)
• $d2o_region_01 $h2o_fraction 0.0008888
• $d2o_region_01 $salt $nosalt (or $added or $grams_per_gram)
• $d2o_region_01 $salt_added 2.e6
• $d2o_region_01 $salt_conc 0.005

This example defines the first region as the D2O region (region type 100). The mass is set to 1.e9 grams and the light water fraction to 0.0008888. Salt is switched off. If the salt flag had been set to $added, the $salt_added value of 2.e6 grams would have been used. If the salt flag had been set to $grams_per_gram, the $salt_conc of 0.005 grams would have been used.

Two regions of heavy water is the default setting. These regions are the heavy water itself, and the inner volume of the acrylic vessel chimney.

The default value of the light water fraction is $0.08$ percent ($99.92$ percent pure D$_{2}$O) in both default regions. The maths used to calculate the number density of the H from that of D is accurate, but assumes that the change in density arises only from the change in mass as $^{1}$H nuclei are substitued for $^{2}$H nuclei. Note that if you issue the command $h2o_in_d2o $off or forget to define a heavy water region, you will get pure D$_{2}$O in that region, very likely a non-physical situation in our detector. Normally the user would not be expected to alter the default settings.

The default value of the salt flag is $nosalt. If salt is added a correction is made to the density of the heavy water based on the salt content. This correction is made using light water data, and assuming the same change in concentration due to atomic effects at the same atoms per atom density in heavy water as in light water.