1. Instrumentation, Controls and MPS
M. Ross October 15, TRC R2:
• The most critical beam instrumentation, including the intra-train luminosity monitor, must be developed, and an acceptable laser-wire profile monitor must be provided where needed. A vigorous R&D program is mandatory for beam instrumentation in general; it would be appropriate for a collaborative effort between laboratories.
Goals for this session:
instrumentation has limited leverage on the design as a whole
inexpensive in dollar terms but not in intellectual terms or testing time.
There needs to be interregional engineering teams to accelerate progress
Performance list of items and their relationship to present state of the art has been made but needs serious engineering input
Understanding of the role of secondary specialized instrumentation also needed.
Commentary on strategy for this RD
Requirements / subsystem re-optimization

2. BPM Typical requirements
linac ~ 75 mm diameter
TDR  10µm
USLCTOPS  1µm (provides much more LET headroom) [NLC
to be revisited by
offset stability?
Beam delivery: much larger diameter, tighter ‘normalized’ resolution requirements
MDI (energy spectrometer)
100 nm stable for many minutes (needs prescription for operation)
DR … both single pass and storage ring hardware needed
ATF 2µm single pass, 25mm
near state of the art

3. Profile monitor – Typical requirements †
micron dynamic range; few percent resolution
dynamic range: useful range of the device (minimal/correctable systematic errors)
resolution: repeatability with given conditions
(how are the above validated?)
(typical SLC ~ 10% at full energy, 5% at DR exit – best condition)
TESLA requirement (N. Walker): 2%
demonstrated at ATF ‘in the ring’: 5µm. – world’s best scanner
large aspect ratio problems  coupling correction
Calibration, Durability, Operability
beyond state of the art needed (?); testing and development of tools important
† not including beam delivery / IR

4. Longitudinal: Correlation monitors
this is where synergy with FEL’s will work best in our favor
There is a ‘huge’ effort underway
Correlation monitors
the next step in understanding emittance growth
projected phase space growth through correlation, e.g. y − z.
Transverse deflecting structures are being used to measure ‘slice emittance’
expensive and cumbersome to integrate
Another beam correlation monitor is required.

5. Back to the source: existing machines
performance (is/has been) limited by BPM resolution / offsets at SLC, LER, LEP and ATF
offsets, resolution and reliability
In the last decade made excellent progress for 3rd generation light sources  averaging and digital receiver techniques. General RD needed for LC. (FEL requirements not equivalent, more relaxed.)
single pass improvements – FFTB, ATF…
TTF relies more on screens
Typical performance:
Storage ring multi-turn – offsets, resolution submicron
single pass (APS – scaled by chamber size to 75mm ILC) ~4um
single pass FFTB (scaled) ~ 3 um / small system

6. Instrumentation RD strategies
to what degree does the ILC rely on instrumentation?
implementation of correction schemes in the TESLA design
TTF (until now) relied heavily on screens, less on BPM’s
testing tolerance limits, understanding resolution ‘budget’
time for RD, time to prove trustworthy systems & reduce risk
profile monitor performance verification /systematics studies
Controlled environment, dedicated test beams (ATF, ESA, rings?)

7. MPS – What is it? the set of all devices which
allow continued smooth operation
provide minimal chance of beam-related component damage
prevent unacceptable levels of residual radioactivity.
Integration of MPS means allocating redundancy to prevent simple single point faults
Generally,
beamline components,
associated sensors,
beam diagnostic devices,
interconnection system
automated fault logging,
recovery sequence,
self-diagnosis used for prediction of beam loss at higher (than current) power.

8. Machine Protection (MPS)
ranked highest risk by USLCTOPS
2 most challenging problems – interconnected with beamline design
single pulse damage
(what are the component by component consequences/results?)  controversial for BD
sequence control / integration
(average power loss protection will be a big, cumbersome system built to mimic existing systems)
impact on component and beamline design (example)
short loop ‘off-ramps’ within BD (looks like ‘FONT’ with fast BPM’s driving powerful kickers)
Use benign leading pilot pulse spaced by a few interbunch gaps to clear system after the ~200ms hiatus (equivalent of MAID from warm)
cold linac  greatest problem is average power (like at TTF2 ~ 20KW at 5Hz/3MHz or 1Hz/10MHz)
Session goals:
dissemination of interconnection issues
RD strategies (test beams, design criteria)

9. MPS Development Process ‘decision tree’:
MPS development will require three stages (USTOPS):
understanding and testing the basic interaction between the beam and beamline components,
development of mechanical engineering guidelines which result in designs that are optimized from an MPS point of view and
development of controls strategies that are at once reliable, redundant and flexible.
Goals for this session:
Agree on the above notes
Commentary on (a) strategy for this RD
System ‘paradigm’ comments