Beam Commissioning

Marco Oriunno (SLAC), May 14, 2014

ALCW 2014, Fermilab

Engineering Issues

2

Possible Commissioning Scenarios

The key requirements originate from a defined strategy for

the commissioning BDS Commissioning, set by the physics

requirements of the Machine and Detectors.

Meanwhile we look at three possible engineering options:

1. w/ Detector

2. w/o Detector, only QF1

3. w/o Detector, QD0 and QF1

3

Challenges and Opportunities

Challenges

• Safety Issues, mainly radiation shielding for a credible

beam loss scenario

• Engineering Issues: Cabling, supports of temporary Beam

Instrumentation.

Opportunities

• Detector-Machine Schedule decoupling

• Leverage on the Push-Pull concept

• Dedicated Machine Development phases

• Opportunity for additional small forward detectors: TOTEM

in the high pseudo-rapidity region ( =h 3÷5) of CMS

4

Option #1: w/ Detector

1. QD0s in place with the corresponding L*

2. Full set of forward detectors (Beamcal, Lumical, etc.)

3. Probably starting with the Vertex detector in place …..the

ATLAS and CMS experience need to be recalled

4. One of the two detectors must be always available for

commissioning and Machine Development:

• How to decide which one, case by case, strictly planned?

• Impact on assembly and maintenance schedule of the

detectors.

5

Option #2: w/o Detector, only QF1

1. Only QF1s with a commissioning optics

2. A basic set of beam instrumentation able to characterize the beam

delivery to the IP (BPM, Beam scanners, etc.)

Option A Permanently integrated in the QF1s regions: minimum impact

on schedule

Option B Movable light skid pre-assembled with the required diagnostic.

Option B cont. Services connection (Cables, Cooling, Cryo) set the

critical path.

Push-Pull : Engineering Concept (Option #1 and #2)

Detector Hall, Japanese Mountain Site

e-

LHe refrigerator and LHe2 for the QD0’s above level on metallic structure.

7

Option #3: w/o Detector, QD0 and QF1

1. Spares QD0s in place with only one L* possible

2. A basic set of beam instrumentation able to characterize

the beam delivery to the IP (BPM, Beam scanners, etc.)

1. Movable light skid pre-assembled with the required

diagnostic.

2. Services connection (Cables, Cooling, Cryo)

3. Possibility of a small-bore/high field MRI solenoid

around the IP for beam distortion studies.

8

Option #3: w/o Detector, QD0 and QF1

1. In normal operations the FFS push-pull with the detectors

together with interconnections (High Current Leads and

Cryogenic)

2. If dedicated QDOs for commissioning are installed, Power

supplies and Cryogenics require not trivial infrastructures.

3. The pumping and the cooling down define the critical path

4. It is eventually a place where the Hybrid FFS Design a-la

CLIC has a strategic advantage.

9

Interface QD0-QF1: Critical for Fast&Reliable Push-Pulls

1 m QF1QD0

Kicker

Cryogenic Penetration

Vacuum Instrumentation

MSL - SLAC 10

20 R.L. Cu target in IP-14 m. Large pacman.

µSv/1_train

Dos

e lim

its

Max

imum

do

se

- The maximum integrated dose per event is ~8 µSv << 30 mSv

- The corresponding peak dose rate is ~140 mSv/h < 250 mSv/h

9 MW

M.Santana, SLAC

11

Pacmen

500 mm Iron2,000 mm Concrete

12

Shielding Wall

13

IP

5 mrad

~40 mrad~85 m

rad

Challenges: High precision, high occupancy,high radiation dose, fast read-out!LumiCal, BeamCal: compact sampling calorimeters, RM~1 cm

Further Physics Opportunities

Precise measurement o the Integrated Luminosity (ΔL/L ~ 10-4).

Provide 2 photon veto.

BeamDiagnostics using beamstrahlung pairs.

Provide 2 photon veto.

BeamDiagnostics using beamstrahlung photons.

14

Summary

Need Machine and Detectors to work on the definition of

BDS commissioning, which in turn will define the set of

requirements for the engineering studies

Three options under study cover the full range of possibility.

1. w/ Detector

2. w/o Detector, only QF1

3. w/o Detector, QD0 and QF1

All options have different challenges and opportunities

EXTRA SLIDES

15

16

Cryogenic Layout : Two options

Plan A : Cold Boxes are stationary. Cold Transfer lines to

each detector. Reliability for push-pull. Not off-the-shelf.

Plan B : Cold Boxes on the platform. Warm Transfer lines to

each cold box. Vibrations, fringe field effects, space

CLID QD0 : Hybrid magnet

Permanent magnet

Why a an Hybrid magnet ?

•Limited space available for the magnet difficult to accommodate a cryostat

•Magnet aperture too small to wind a superconducting cables given the large forces and the small radius;

•Complex assembly, difficult to align and stabilize at the sub-nanometer level (different layers of coils, collars, thermal insulation, cryostat);

•Difficult integration of a conical post-collision line in a cryostat assembly.

ILC QD0 : Cold Mass 2K Helium (BNL)

~3.5 m

• Technology of the superconducting final focus magnets has been demonstratedby a series of short prototype multi-pole coils.

• QD0 magnet split into two coils to allow higher flexibility at lower energies.

• The quadrupoles closest to the IP are actually inside the detector solenoid.

• Actively shielded coil to control magnetic cross talk•Additional large aperture anti-solenoid in the endcap region to avoid luminosity loss due to

beam optics effects. • Large aperture Detector Integrated Dipole (DID) used to reduce detector background

at high beam energies or to minimize orbit deflections at low beam energies.

Magnetic Field compensations at IP, DID, antiDID

QD0

QD0

Pairs distributions at 3.5m from IP

anti-DID ONanti-DID OFF

IP

-1

0

1

2

3

4

-12 -10 -8 -6 -4 -2 0

ILD, l*=4.5 m

Bz (T)

z (m)

SF1 QF1 DIPSD0 QD0

-2

-1

0

1

2

3

4

5

6

-12 -10 -8 -6 -4 -2 0

SolenoidSolenoid+anti-solenoidanti-solenoid

SiD, l*=3.5 m

Bz (T)

z (m)

SF1 QF1 DIPSD0 QD0

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06

-12 -10 -8 -6 -4 -2 0

ILD Solenoid

Anti-DID

ILD Solenoid+anti-DID

z (m)

SF1 QF1 DIPSD0 QD0

Bx (T)

SF1 QF1 DIPSD0 QD0

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

0.05

0.06

-12 -10 -8 -6 -4 -2 0

SiD Solenoid

Anti-DID

SiD Solenoid+anti-DID

Bx (T)

z (m)

• Longitudinal field of the solenoid + Fringe field extending over QD0 -> coupling (x, y) (E,y) => beam size growth• Radial field due to crossing angle -> orbit deviation, implying synchrotron radiation,• Fringe field extending over QD0 -> no compensation of radial and longitudinal components, => non zero orbit at the IP

• Anti-DID field -> additional radial field deviating incoming particles.

R. Versteegen

Site Delivery prior the start of the Detector Assembly