[Gate-users] Generic repeater for spectHEAD - received a hit with wrong head

[Steven Marsh]

Hi Etienne et.al.

Thank you for your reply. Based on your advice I have attempted the use of the generic repeater to produce four spectHead detectors.  It appeared to work well until attempting to produce projection data for each head independently.  At this point I noticed that the projection data contain data representative of a single head and I get the error message ...

[GateToProjectionSet::Fill]:
Received a hit with a wrong head ID (1): ignored!
[GateToProjectionSet::Fill]:
Received a hit with a wrong head ID (1): ignored!
[GateToProjectionSet::Fill]:
Received a hit with a wrong head ID (3): ignored!
[GateToProjectionSet::Fill]:
Received a hit with a wrong head ID (3): ignored!
[GateToProjectionSet::Fill]:
Received a hit with a wrong head ID (2): ignored!
[GateToProjectionSet::Fill]:
Received a hit with a wrong head ID (2): ignored!

Any help on this one would again be greatly appreciated.
Steve



Hello Steve,

As you found out, I do not think it is possible to apply a ring repeater on an already "ring repeated" volume. But I think you still have at least two options to achieve what you want here.

1) If it does not bother you to define again the same SPECThead with a different name (e.g. SPECThead2), you could just apply another ring repeater to this new volume, by specifying the starting angle as 180 deg :

/gate/SPECThead2/repeaters/insert ring
/gate/SPECThead2/ring/setFirstAngle 180 deg # this line is important to achieve what you want!
/gate/SPECThead2/ring/setAngularSpan 76 deg /gate/SPECThead2/ring/setRepeatNumber 2

2) If you absolutely want to keep a single definition of your SPECThead, then you could have a look at the generic repeater, which could be a good option for you also since you only have to calculate the rotations and translations needed to position four volumes on a circle : https://opengate.readthedocs.io/en/latest/defining_a_geometry.html?highlight=ring%20repeater#generic-repeater.

In the hope that this answer will help you,