Knowledge of muon momentum is assumed during X0 inference

[GilesStrong]

Current status

X0Inferer.x0_from_dtheta requires MuonBatch.reco_mom in order to compute X0 during the scattering inversion, however MuonBatch.reco_mom simply returns the gen.-level momentum MuonBatch.mom. In actual application, the momentum of the muons must be estimated.

Possible solution

According to @giamman (please correct if wrong), this is usually achieved by placing material of known X0 below the detector under the passive volume, and then adding a third detector layer; scattering in the second passive volume can then be used to invert the scattering formula in terms of momentum, and then the reco momentum can be used to estimate the X0 in the first passive volume.

This can be achieved in code by slightly generalising ScatterBatch to use user-specified hit locationsand then using a class similar toX0Infererto infer the momentum, and update the muon-batch properties prior to running the X0 inference. Generalisation and checking of theVolumeandVolumeWrapperclasses will be required to account for the two passive volumes. Additionally, the second passive volume could be constructed from a newLayer` class, and the material used could be an optimisable parameter.

[giamman]

That's correct, this is a popular way to estimate the momentum. The addition of a class such as you propose, i.e. that infers momentum given X0 instead of the other way around, would allow for the optimization of also the part of the apparatus that is designed to do that. Cheers, Andrea

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------------------------------------------------------- Andrea Giammanco http://cp3.irmp.ucl.ac.be/Members/giammanco Phone: +32 10 473221 (UCLouvain), +32 493 581662 (mobile)

________________________________ From: GilesStrong ***@***.*** Sent: 02 June 2021 13:05 To: GilesStrong/mode_muon_tomography Cc: Andrea Giammanco; Mention Subject: [GilesStrong/mode_muon_tomography] Knowledge of muon momentum is assumed during X0 inference (#41) Current status X0Inferer.x0_from_dtheta requires MuonBatch.reco_mom in order to compute X0 during the scattering inversion, however MuonBatch.reco_mom simply returns the gen.-level momentum MuonBatch.mom. In actual application, the momentum of the muons must be estimated. Possible solution According to @giamman<https://github.com/giamman> (please correct if wrong), this is usually achieved by placing material of known X0 below the detector under the passive volume, and then adding a third detector layer; scattering in the second passive volume can then be used to invert the scattering formula in terms of momentum, and then the reco momentum can be used to estimate the X0 in the first passive volume. This can be achieved in code by slightly generalising ScatterBatch to use user-specified hit locationsand then using a class similar toX0Infererto infer the momentum, and update the muon-batch properties prior to running the X0 inference. Generalisation and checking of theVolumeandVolumeWrapperclasses will be required to account for the two passive volumes. Additionally, the second passive volume could be constructed from a newLayer` class, and the material used could be an optimisable parameter. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub<#41>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ABFT2LVDBJJ646DF7EPPS4DTQYF6ZANCNFSM456P6NBQ>.