<div dir="ltr"><div dir="ltr">Dear colleagues,<div><br></div><div>There are two separate problems to be addressed regarding the use of hdgeant in the post-DIRC era.</div><div><ol><li>how to run pre-DIRC geometry, when the DIRC is present in the master branch of hdds</li><li>how to run with the DIRC present, but not suffer the overhead of following CKOV photons</li></ol><div>For #1, please see my howto at <a href="https://halldweb.jlab.org/wiki/index.php/HOWTO_run_hdgeant_simulations_using_ccdb_geometry">https://halldweb.jlab.org/wiki/index.php/HOWTO_run_hdgeant_simulations_using_ccdb_geometry</a></div></div><div><br></div><div>For #2, I recommend that you go into your <a href="https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fcontrol.in&data=02%7C01%7CHallD-Offline%40jlab.org%7C825ddda3575245f61a1608d6861220d5%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C0%7C636843809750190056&sdata=E7L48O1v7PlJqXQP2g%2FeePZznjNJN8UoAv4nsMEHrk0%3D&reserved=0" originalSrc="http://control.in" shash="VvBjEsj8r4rM0MT5RHo6LWFF9/ieW4npuOloCCjMoJ2oVnTgcTeqJJOSVJWLtbnwQFjeR4tBGYYeqNhglD8Y3IiFG0CbRDS6M35bKIo6YT1uadaJ53Ov6QCE20RwMoB8pI0KaaIKC2UwRJGt2/T6WQNYFhRQZLtSUgkSk9pE6Kc=">control.in</a> and change CKOV 1 to CKOV 0. I could force this in the code, but there are situations where it would be useful to have them enabled, and that is what the CKOV flag is there for. As soon as you turn CKOV 0 in your <a href="https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fcontrol.in&data=02%7C01%7CHallD-Offline%40jlab.org%7C825ddda3575245f61a1608d6861220d5%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C0%7C636843809750200070&sdata=iMg9E6jrEJUmasMxXLHZKLxzCtWXvZ2XxWU7pWN2Dws%3D&reserved=0" originalSrc="http://control.in" shash="Jgzwtq4I/KzUZ453rhtILmHtr4lz1yETjDRa/T5nsFNu2SLBHhTI91BnV5DMvjdBxIKpbI38vJoS/ywWfOToBd9U1tbujC7dK+iY4oZ+R8DIOri4C1jXnQQdsKEg7Mr0dUib5VKXa9BvOek7W2hM0UcP0ZoySiFixauAE8OU9ts=">control.in</a>, the overhead associated with the DIRC will disappear from your simulation and you will have the material present but not the slow-down.</div><div><br></div><div>Setting CKOV 0 rather than hard-wiring it in the code makes sure that you are making simulations that are directly comparable between hdgeant and hdgeant4 when running on the same <a href="https://na01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fcontrol.in&data=02%7C01%7CHallD-Offline%40jlab.org%7C825ddda3575245f61a1608d6861220d5%7Cb4d7ee1f4fb34f0690372b5b522042ab%7C1%7C0%7C636843809750200070&sdata=iMg9E6jrEJUmasMxXLHZKLxzCtWXvZ2XxWU7pWN2Dws%3D&reserved=0" originalSrc="http://control.in" shash="Jgzwtq4I/KzUZ453rhtILmHtr4lz1yETjDRa/T5nsFNu2SLBHhTI91BnV5DMvjdBxIKpbI38vJoS/ywWfOToBd9U1tbujC7dK+iY4oZ+R8DIOri4C1jXnQQdsKEg7Mr0dUib5VKXa9BvOek7W2hM0UcP0ZoySiFixauAE8OU9ts=">control.in</a>. This is a design feature.</div><div><br></div><div>-Richard Jones</div></div></div>