1. Specifications for Central Region Layout
Based on discussions held at FNAL on August 10-11, 2011
Date Event
Global Design Effort

2. Central Region - Transition
Mid-plane
Section C: Horizontal arc of ~26 deg
DR Inj/Ext Straight
Section D: Straight containing energy
compressor. Length to be set by the separation between DR and main tunnels.
Section A:
Injection/Extraction lines to/from the DR.
Horizontal bend only.
Approx. 30m long.
Exit angle approx. 243mrad = 13.9deg
Section B: Vertical manipulation section for positron and electron injection and positron extraction. No
horizontal changes!
Nominal 75m length.
To ML Tunnel
Section E:
39.5deg (5 x 7.9deg) arc for spin rotation of injected beam.
Relative Injection & Extraction Locations: e+ = red, e- = blue
PLTR
ELTR
Date Event
Global Design Effort

3. Section A Description: DR injection/extraction lines
Design Ownership: Damping Rings Group
Key features:
Starts at extraction/injection septa with initial separation angle from DR ~105mrad
Nominal exit angle into ELTR/PLTR tunnels is ~240mrad (1 bend magnet) with h=h’=0
Horizontal length of each line ~27.2m (septum to start of ELTR/PLTR tunnel)
Injection/extraction lines to be adjusted to provide same horizontal angles at start of ELTR/PLTR tunnels (~240mrad) with 1m transverse separation between lines along the axis of the tunnel
Date Event
Global Design Effort

4. Section B
Description: e+ Merger/Splitter & Vertical Escalator Straight (nom. 75m length)
Design Ownership:
RTML group owns splitter/merger optics design
Optics based on vertical dogleg design at end of RTML turnaround (see N. Solyak slides p. 10). Note that this multiple bend design should minimize pulsed element strength requirements.
DR group to help with pulsed element specification
e- source group owns injection line to Section A boundary
e+ source group owns injection line to start of splitter section
RTML group owns extraction lines from Section A boundary
Key features
Splitter/merger optics based on RTML design
Source groups will have responsibility to adjust vertical height to RTML height in this section
Date Event
Global Design Effort

5. Section C
Description: Arc to match “S-curve” transition from DR tunnel to central tunnel
Design Ownership:
RTML group owns optics for beam lines heading away from the DR
Source groups own optics for beam lines heading towards the DR
Key features
In order to maintain parallel beam lines in tunnel, proposal is to run “inside track” beam line with R=30m and “outside track” beam line with R=31m (arrangement to be reversed in Section E)
Date Event
Global Design Effort

6. Section D
Description: Energy compressor and spin rotation straight (length to be determined by separation between DR and main tunnels)
Design Ownership:
Lines heading towards the DR owned by corresponding source group
Lines heading away from the DR owned by the RTML group
Key Features:
Principal hardware in this region is for the e+ energy compressor and completing the spin rotation to vertical for injection into the DR
The length of this straight will be adjusted to match the separation between the axes of the DR Inj/Ext straight and the main tunnel
Date Event
Global Design Effort

7. Section E
Description: Horizontal arc for spin rotation – this is 5 units of 7.9° rotation for 39.5° total
Design Ownership:
Sources group owns lines heading to DR
RTML group owns lines heading away from DR
Key Features:
The ends of this section must include suitable drift space to match to the sources and RTML lines which do not run along the same axis in the main tunnel
Date Event
Global Design Effort

8. Personnel Assignments
Cornell group will review injection/extraction lines and placement as part of DTC lattice work
Valeri Kapin will design splitter/merger optics
Mark Palmer will prepare pulsed element specifications for circulation to experts
Wanming Liu will modify positron source optics to match new layout up to positron splitter location (middle of section B)
Need input from John Sheppard on modification of electron source optics to match new layout up to the sections A-B boundary
Nikolay will oversee overall modification of RTML optics from sections A-B boundary
CFS group will determine length of straight section D as soon as physical constraints (eg, minimum allowed spacing between DR Inj/Ext straight and detector hall) are fully understood
Ewan/Mark will continue to help coordinate.
Date Event
Global Design Effort

9. Key Milestones/Deliverables
Week of Aug 15
Section descriptions (this document) – Mark
Updated tunnel layout – CFS Group
Arrange joint meeting at Granada (Vic, Mark, Nikolay, Wei, John)
August-September
Develop optics and layouts for all sections (A-E)
Obtain input on pulsed element options from experts
Granada
Review of optics and layouts for all sections (A-E)
DESY meeting
Documentation complete
Freeze central region layout
Date Event
Global Design Effort