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

2. 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

3. 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

4. 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.

5. 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)

6. 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

7. 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)

8. 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

9. 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

10. 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

11. 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)