Review of Detector Solenoid Effect to the Beam

• Effect on Beam Orbit

• Effect on Beam Size

S.Kuroda(KEK)

Solenoid Effect on Beam Orbit• Sharp edge approximation Finite crossing angle with offset LcOffset@IP y=0 y’=-: No effect on Luminosity for e+e-, but need compensation for e-e- Need compensation for post IP polarimetry

=B0 c/(2 B)

y’= -2 for extracted beam must be also considered in extraction line design.

[B.Parker, A.Seryi]

Correction of the Orbit Offset2 correctors K1=/(1-L1/L2) ( inside sol.) K2= - /(L2/L1-1)( outside sol.)

Extracted beamy’=−Θ(2 + 1/(L2/L1 − 1))

[B.Parker, A.Seryi]

Detector Integrated Dipole(DID)• Real solenoid field extends and overlaps to FD.• Correction by FD offsetLarge orbit distortion Correction should be done locally(y changes inside solenoid) DID

DID: Co-winding with solenoid in cryostat 1. Smaller B radiation Length in detector acceptance 2. Avoiding torque(forces) between solenoid and B when B is introduced separately. 3. Large bore good uniformity in beam region

DID+FD offset IP angle compensation

[B.Parker]

Solenoid Effect on Beam Size

• Effect due to synchrotron radiation

SR ~ (B0 c L)5/2 F(optics) [PRSTAB-061001] (independent on beam energy) for c =20mrad full x-ing angle:SR = 0.31 nm in SDSR = 0.57 nm in LD where is understood as =sqrt[02 + 2]

• Overlapping effect of Bz to FD1. Real solenoid field extends and overlaps to FD Beam size growth

2. Independent on c

LD Bz profile

LD model, = 20 mrad LD model, = 0

[Y.Nosochkov, A.Seryi]green:no solenoidred:with solenoid

•Beam size compensation

Correction can be done using skew Q & SX displacement y/y0~1.03This correction method is difficult when E is very low.

SiD case only orbit cor.

Beam size cor.by SQ,SX…

[B.Parker, A.Seryi]

Example of LD solenoid compensation using two weak antisolenoids (2.26 and 0.07 Tm) placed at two FF quads.

Total field with and w/o antisolenoids

IP phase space with antisolenoid correction , y = 23%

With antisolenoids and linear knobs, y = 0.9%

[Y.Nosochkov, A.Seryi]

•IP distortion & beam size compensation for SiD(DID & anti-solenoid)

Additional B BXMID introduced

Beam size is corrected to y/y0~1.01by anti-solenoid and skew Q

Knob strength is relaxed by anti-solenoid

Summary• For non-zero x-ing angle, solenoid field will make finite y’ @IPy’ should be zeroed for e-e- collision/post IP polarimetry A corrector in solenoid region is needed( e.g. DID )

• Beam size growth due to overlapping solenoid field to FD ( indep. on x-ing angle ) >> Beam size growth due to synchrotron rad. Anti-solenoid method excellently compensates this effect ( down to low E )