Summary of wg2a (BDS and IR) Deepa Angal-Kalinin, Shigeru Kuroda, Andrei Seryi October 21, 2005

Summary of wg2a(BDS and IR)

Deepa Angal-Kalinin, Shigeru Kuroda, Andrei Seryi

October 21, 2005

2 21 Oct 05wg2a summary, A.Seryi

Topics and talks• Since Snowmass, concentrated on configuration with

intermediate crossing angle (14mrad) for single IR, now have the design – Status of extraction 14mrad optics -- Tom Markiewicz– IR optics optimization, FD optics, DID, anti-DID -- Andrei Seryi – BDS civil layouts & upgrade from single IR to two IR -- Andrei Seryi – Design of magnets for 14mrad -- Brett Parker (wg2d)

• Continue development of 2mrad design– Update on 2mrad design -- Deepa Angal-Kalinin

• Continue design of various BDS systems– Thoughts on Linear Collider Fast-Abort Systems -- Tom Mattison – Crab cavity status -- Deepa Angal-Kalinin – Diagnostics length, laser wire requirements – D.Angal-Kalinin,

G.Blair

• New developments and critical considerations– Alternative Design for Collimation System -- Angeles Faus-Golfe – IR design issues -- Tom Markiewicz

(wg1)


Two IR baseline & single IR alternative

• Baseline has two Beam Delivery Systems, two collider halls separated in z by ~130m, for two independent experiments

• The paradigm of two BDS, two IRs, two collider halls and detector is challenged and likely will be changed

• The considered alternative is single IR, single or two push-pull detectors, at least at the start of ILC, with clear plan how to upgrade to two IRs

• The intermediate crossing angle (~14mrad with L*=3.5m) considered for single IR alternative would provide– separate incoming & extraction line – flexibility of design and operation, higher luminosity reach – clean downstream diagnostics– higher detector hermeticity in comparison with 20mrad– background can be as good as in 2mrad IR



• In recent extraction design for 14mrad, the self shielding quads are used – no interference between in and out beamlines


2005 SiD for 20mrad, coordinates at IP:y= -20.7m -- easy to compensate y’= -97.5 rad

• With crossing angle, solenoid cause Y orbit

• e+e- beams still collide head-on

• Spin rotation 3 degrees

5T

IR optimization

e-

e+

Y orbit in solenoid


DID field

Standard DID

• Coil wound on detector solenoid, giving transverse field, such that combined field from solenoid, Detector Integrated Dipole, and QD0 would be result in 0 vertical angle at the IP


sr =0.19nm (20mrad)y‘ and y at IP are zeroed

Standard DID

• For standard DID, can zero y and y’ at IP

• Correction is local and very effective

• No increase of SR• But the post IP field is

about doubled by DID, so pairs would disperse more

IP

IP

e-

e+

z


anti-DID for intermediate crossing angle

• Normal polarity of Detector Integrated Dipole (DID) allows to compensate locally the effect of crossing the solenoid field for the incoming beam, while the field seen by outgoing beam (and low energy pairs) about doubles

• Reversing polarity of Detector Integrated Dipole (anti-DID) could effectively zero the crossing angle for outgoing beam (and pairs) but would increase it (1.5-1.6 times) for incoming beam

• Increasing the effective crossing angle for incoming beam may create too much synchrotron radiation size growth (which depend as SR5/2)

• Smaller initial crossing angle (14mrad) ease the use of anti-DID


Normal DID & SiD

• With normal DID, which is optimized for incoming beam, the high energy pairs go to extraction aperture, but low energy pairs directed away from extraction aperture

Shown trajectories of pairs and their distribution at z=3.5m


• High energy pairs follow initial beam trajectory, and go to extraction aperture

• Low energy pairs follow the field line, and >60% go to extraction aperture

Use Guinea-pig pairs for nominal ILC parameters

anti-DID in SiD detector


anti-DID for GLD detector• With optimal anti-DID, more than 50% of pairs are

directed into the extraction aperture => better background

• Similar improvement is possible for LDC detector

Optimal anti-DIDNormal DID


Optimal anti-DID for GLD

• Field in the central region is flattened with two DID coils (short and long) whose currents are properly adjusted, to ease TPC calibration

• Field in the central region (|z|<0.5m) decreased ~65 times


QD0

QDEX1AQDEX1B

QFEX2A

14 mrad crossing Geant model of SiD

• Takashi Maruyama modeled SiD with 14mrad and anti-DID


2, 14, 20 mrad400

300

200

100

0

VX

D H

its

/ BX

54321

Layer

2 mrad14 mrad20 mrad

ILC 500 GeV Nominal beam parameters

14 mrad crossing – DID/Anti-DID

400

300

200

100

0

VX

D H

its

/ B

X54321

Layer

No DI D DI DAnti-DI D

VXD Hit comparison

Takashi Maruyama

• DID or anti-DID – the VXD hit rate is very similar


Photons into Tracker

• Pair energy into BeamCal is smaller in 14 mrad crossing.

• Anti-DID can further reduce the energy to the 2 mrad crossing level.

• # of secondary photons generated in BeamCal is also smaller.

80

60

40

20

0

Beam

Cal E

nerg

y (T

eV)

3.02.52.01.51.00.50.0

Beampipe Radius (cm)

2 mrad 20 mrad 14 mrad 14 mrad + DI D 14 mrad + Anti-DI D

# photons/BX into Tracker

14 mrad 14 mrad+ DID

14 mrad+ Anti-DID

2 mrad

1800 1900 830 720

Takashi Maruyama


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.

Single IR & upgrades

• 14mr single IR can be upgraded to two IRs:– 14mr & small crossing angle, min or large

separation between detectors– 14mrad and large crossing angle, good for

gamma-gamma

• CF group started to consider such upgrades

A

B

C










BDS and IR design summary• Since Snowmass, made a lot of efforts to design

an alternative with min crossing angle which is– compatible with compact BNL quads– provides separate incoming and extraction lines– compatible with high luminosity and reliable and flexible

operation

• Design of optics and magnets for 14mrad complete, background is improved and is as low as in 2mrad case

• Continue design of BDS sub systems such as extraction, abort system, crab cavity, optimization of collimation, etc.

• Continue evaluation of issues of global layout • Critical review of what we are doing is useful and

needed

Documents

Summary of wg2a (BDS and IR) Deepa Angal-Kalinin, Shigeru Kuroda, Andrei Seryi October 21, 2005