EMBT to EHAT (inclusive) Beamline Document Review: Recommendations

Introduce page numbers.


Include citations [1,2,…] with correspondences in the References section.

E.g. Beam Diagnostics Requirement document, ELBT DN, ARIEL high-level requirements.

Explain in 3 sentences phases 1a (EACA), 1b (EACA+EACB), 2 (Ring)

Name explicitly the 1st and last elements that delimit the scope of this note.

Thetable of beam properties is a system of constraints (not requirements) arising from the upstream ELBT and EINJ. The requirement is that you match the EMBT etc to ELBT; and that loss be <10-5/m.


These should be recapitulated and referenced.

Design Note versus Solution Note

This is supposed to be a "design" note. What was presented is a "only the solution" note.

One would expect to find a summary of the challenges, followed by a description of the design strategy; what options and choices were considered. It does not have to be lengthy, but it should be there in brief, broad strokes – on a per section basis.

Definitions and Tolerances

State the closed orbit tolerances which drive the correction scheme.

State the installation tolerances for pitch, roll, yaw of magnets, particularly quadrupoles.

State the longitudinal and transverse (to the beamline) magnet installation/alignment tolerances according to type and location.

Explain the relation between absolute X, Y and  relatives,r” measured along/transverse beamline – and what are the relevant precisions (# digits after decimal point).

What is truly immutable? It may prove useful to define articulation points at which the local reference frame is rotated. Eric to confirm with DO if this would be useful.  Eric to confirm that DO definitely do not want “s,r”.

State assumptions on magnet insertion lengths for each type.

Document needs a statement on the location of cryomodules: E.g. cryomodule length is XX, and entrance and exit face cords are: YY, ZZ.

Priority of documents

Consensus:  The consolidated list of coordinates EGUN to EHDT and EHBT to Targets, has priority over the DN’s between re-release of a beamline DN.

The consolidated list will require re-release (when? Based on what criterion?) Eric to determine.

Beamline DNs will only be re-released if designers request, and optics agrees, to equipment movements greater than tolerances stated in the Beamline DN.

Beamline Sections

State that drawing is illustrative. Insert PDF of Stu’s entire e-hall layout and reference its sections rather than reproduce individual segments.

Vertex of main line and stub line should be at “centre” of dipole that initiates stub. Update drawing!

E.g. EMBD0:MB0 and EABD:MB0

[Even this is not quite correct, since optics group propose offsets of dipoles to reduce aberrations. This must be tabulated when the dipole designs are frozen.]

Magnet strength “margins”

Motivate in a few sentences the 25% (or other) magnet strength margin at each occurrence.

Rick’s statement: margin up to 15% needs no additional motivation.

Dipole orientation

All dipoles are rectangular. Make statement that all entrance and exit angles are equal; immutable condition for DO layout.

Tables of Diagnostic devices

Screen to be added either at 5A (collimator) or 5B (wire) – according to engineering feasibility.

Include all diagnostic devices phase1a+phase1b+phase2 so that diagnostic boxes may be rationalized (e.g. DO choose number of ports). Denote equipment for later phases (1b, 2) by asterisk or other annotation.

Introduce statement that devices sharing the same coordinate refer to “IN” versus “OUT”. For example, the RF shield is “IN”, when the view screen (VS) is “OUT”.

Field Compensation Coils

State that they are present (or not) – but do not discuss their design here.

High-power Faraday Cups

The EMBD and EABD terminate in high-power (3kW) Faraday cups, and it is long known that these are specialized devices not suitable for standard diagnostic boxes used at VECC.

Victor cautions that the in-line, low-power Faraday cups (300 W) for high energy operations (30, 50, 75 MeV, etc) are not simple devices despite their apparent low power – because of the long penetration depth of the high energy electrons into the collector materials. Hence specialist boxes may be needed, or the strategy re-thought.

This caution does not affect Y.C. Chao’s design note, but will manifest in the beam diagnostic group response to request for these devices.

Overall Summary

With some revision, this document will be able to serve as the basis for geometrical layout from EMBT to EHAT; and will become adequate to that purpose for the Design Office.

It is not clear that the note provides complete information for the beam diagnostic design. It was noted that maximum diagnostic box insertion lengths could be computed automatically from coordinate lists. This would be a useful addition to the Tables.

Eric, Shane, etc, must determine whether an additional document is needed. Victor and Andy proposed the “Diagnostic Request” template as a starting point.