BDS civil construction Single IR upgrade scenarios discussion Andrei Seryi October 11, 2005

Single IR baseline and upgrade Assume baseline is single IR with 14mrad Upgrades : A) 14mrad and small angle, min separation between detector, no room for shielding B) 14mrad and small angle, larger separation between detectors, shielding OK, but adds ~1km or more to the BDS length C) 14mrad and 20mrad (or more), gg, large separation between detectors

Single IR baseline features 14mrad crossing angle at IR Assume linacs angle is 14mrad as well In principle compatible with linacs oriented along the same line, if dictated by a particular site, division point at ~2700m Can have single or two push-pull detectors Tunnel stubs included which allow upgrade to have two detectors in a single IR that can be chosen much later

Single IR with 14mrad Tunnel stubs for beam dump Tunnel stubs for future upgrades. At first stage can be used as alcoves for diagnostics electronics, lasers for laser wires, etc.

Upgrade to two detectors, Version A 14mrad and 0-2mrad Min separation between detector (assume their Δ=Ø=~15m), no room for shielding Detector cannot be serviced independently For disassembly, detectors first need to be moved out But this version saves ~1-2km of the BDS length (~30-60GeV CM higher energy reach)

Upgrade A: 14mrad & small xing Detectors are placed with min separation, no shielding in between The middle tunnel stub was used to continue tunnel to 2nd IR

Upgrade to two detectors, Version B 14mrad and 0-2mrad Large separation between detector, sufficient room for shielding Detector can be serviced independently For disassembly, detectors may stay on place But this version adds ~1-2km to the BDS length (~30-60GeV CM lower energy reach)

Upgrade B: 14mrad & small xing Detectors are placed with larger separation, sufficient to have shielding in between The first tunnel stub was used to continue tunnel to 2nd IR BDS is lengthened by 1-2 km

Upgrade to two detectors, Version C 14mrad and 20mrad (or more) Large separation between detector, sufficient room for shielding Detector can be serviced, constructed, assembled independently, on place Gamma-gamma compatible

Upgrade C: 14mrad and larger xing The middle tunnel stub was used to continue tunnel to 2nd IR Detectors have large separation, sufficient for shielding and to construct the gg detector on place

Discussion The assumes single IR baseline with 14mrad can be upgraded to A) 14mrad and small angle, min separation between detector B) 14mrad and small angle, larger separation between detectors C) 14mrad and 20mrad (or more) large separation between detectors, OK for gg Need to discuss possible civil construction issues and feasibility of closely placed detectors in B)