Change M1 chamber frame material to iron to improve the MC/Data agreement for M1 occupancy
See LHCBCNDB-586
Note: branches dt-2016, dt-2015, dt-2018 should be updated to match dt-2017 after this MR is applied.
Edited by Marco Clemencic
See LHCBCNDB-586
Note: branches dt-2016, dt-2015, dt-2018 should be updated to match dt-2017 after this MR is applied.