[PPT] - IAS Program on High Energy Physics Polarization Free Methods for PowerPoint Presentation

SLIDE 1

IAS Program on High Energy Physics Polarization Free Methods for Beam Energy Calibration

Nickolai Muchnoi

Budker INP, Novosibirsk

January 20, 2016

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 1 / 20

SLIDE 2

TALK OUTLINE

1

Introduction

2

Extending beam energy range?

3

Conclusion

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 2 / 20

SLIDE 3

Introduction

FCC-ee/CEPC aims to improve on electroweak precision measurements, with goals of 100 keV on the Z mass, and a fraction of MeV on the W mass. The resonant depolarization technique is the only known approach that showed the accuracy at the level of ∆E/E ≃ 10−6. My personal experience is based on beam energy measurement systems for VEPP-4M, BEPC-II and VEPP-2000 colliders. I will try to extend this approach for higher energies.

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 3 / 20

SLIDE 4

Inverse Compton Scattering

θε

e l e c t r

n

: ε photon: ω photon: ω0 electron: ε0, γ=ε0/m

θω Scattering parameters, u and κ: u = ω ε = θε θω = ω ε0 − ω; u ∈ [0, κ] ; κ = 4ω0ε0 m2 . Scattering angles: θω = 1 γ κ u − 1; θε = 4ω0 m

u

κ

1 − u

κ

.

Maximum energy of scattered photon (θω = θε = 0): ωmax = ε0κ 1 + κ. ε0 = ωmax 2

1 +
1 + m2/ω0ωmax
≃ m

2 ωmax ω0 .

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 4 / 20

SLIDE 5

Laser backscattering for beam energy calibration

HISTORY: Taiwan Light Source1996, BESSY-I,II1998,2002, VEPP-3,4M,20002008,2005,2012, BEPC-II2010, ANKA2015

e. g. BEPC-II HPGe spectrum

, keV

γ

E 1980 2000 2020 2040 2060 2080 100 200 300 400 500 600 700 800 900 /NDF = 294.5/296

2

χ 0.12: ± = 1.31 K 0.20 keV ± 0.12 ± = 2025.42

max

ω

mτ =1776.91±0.12+0.10

−0.13MeV

Phys. Rev. D90 (2014) 012001
e. g. VEPP-2000 HPGe spectrum

, keV

γ

E

1650 1700 1750 1800 1850 1900 1950

counts

500 1000 1500 2000 2500 3000 3500

2012.04.20 (16:21:34 - 18:53:59) 2012.04.20

Backscattering occurs inside the magnet: evident interference

Phys.Rev.Lett. 110(2013) 140402

✞ ✝ ☎ ✆

Achieved accuracy is ∆E/E ≃ 3 × 10−5 for E < 2 GeV

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 5 / 20

SLIDE 6

Accurate energy scale transfer: eV → MeV → GeV

IR optics, 10P20 CO2 laser line: ω0 = 0.117065228 eV γ-lines from excited nuclei as a good reference for ωmax:

137Cs

τ1/2 ≃ 30.07 y Eγ = 0661.657 ± 0.003 keV

60Co

τ1/2 ≃ 5.27 y Eγ = 1173.228 ± 0.003 keV Eγ = 1332.422 ± 0.004 keV

208Tl

τ1/2 ≃ 3 m Eγ = 2614.511 ± 0.013 keV

16O∗

Eγ = 6129.266 ± 0.054 keV High energy physics scale1: J/ψ 3096.900 ± 0.002 ± 0.006 MeV ψ(2S) 3686.099 ± 0.004 ± 0.009 MeV

1Final analysis of KEDR data, Physics Letters B 749 (2015) 50-56

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 6 / 20

SLIDE 7

1

Introduction

2

Extending beam energy range?

3

Conclusion

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 7 / 20

SLIDE 8

Spectrometer with laser calibration

Xedge Xbeam

BPM

X0

BPM C

m

p t

n

p h

t
n

s DIPOLE MAGNET L A S E R B E A M Compton electrons with min. energy e l e c t r

n

b e a m

Δθ

θ

BPM Here tiny fraction

f the beam electrons

are scattered on the laser wave

L

BPM BPM BPM Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 8 / 20

SLIDE 9

Spectrometer with laser calibration

Xedge Xbeam

BPM

X0

BPM C

m

p t

n

p h

t
n

s DIPOLE MAGNET L A S E R B E A M Compton electrons with min. energy e l e c t r

n

b e a m

Δθ

θ

BPM Here tiny fraction

f the beam electrons

are scattered on the laser wave

L

BPM BPM BPM

∆θ θ = κ = 4ω0E0 m2

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 8 / 20

SLIDE 10

Spectrometer with laser calibration

Xedge Xbeam

BPM

X0

BPM C

m

p t

n

p h

t
n

s DIPOLE MAGNET L A S E R B E A M Compton electrons with min. energy e l e c t r

n

b e a m

Δθ

θ

BPM Here tiny fraction

f the beam electrons

are scattered on the laser wave

L

BPM BPM BPM

Access to the beam energy: E0 = ∆θ θ × m2 4ω0 ∆θ θ = κ = 4ω0E0 m2

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 8 / 20

SLIDE 11

Spectrometer with laser calibration

Xedge Xbeam

BPM

X0

BPM C

m

p t

n

p h

t
n

s DIPOLE MAGNET L A S E R B E A M Compton electrons with min. energy e l e c t r

n

b e a m

Δθ

θ

BPM Here tiny fraction

f the beam electrons

are scattered on the laser wave

L

BPM BPM BPM

Access to the beam energy: E0 = ∆θ θ × m2 4ω0 E0 =100 GeV, ω0 =1 eV: ∆θ θ ≃ 1.53

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 8 / 20

SLIDE 12

What do one has from ∆θ measurement?

✎ ✍ ☞ ✌

∆θ m2 4ω0 = 1 c

Bdl

∆θ is a measure of a B-field integral along the trajectory which is very close to the beam orbit (see next slides). ∆θ is independent of beam energy: fast energy changes may be detected by BPMs. I. e. increase of ∆θ measurement time does not influence the beam energy measurement accuracy. Measurement of θ is outside of this talk. One can have a look at the experience of LEP spectrometer as well as ILC beam energy spectrometer studies.

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 9 / 20

SLIDE 13

Two arcs in a dipole of length L

Re L ΔX R

θ

Δθ

Note that

✞ ✝ ☎ ✆

Re = R0/(1 + κ). S0, R0 – black arc length & radius, Se, Re – red arc length & radius. So S0 = 2R0arcsin L 2R0

and

Se = 2Rearcsin √ L2 + ∆X2 2Re

,

where ∆X =

R2

e −

LRe 2R0 2 −

R2

e −

L − LRe

2R0 2 .

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 10 / 20

SLIDE 14

Apparatus: general consideration

L 20 m 20 m

ΔX

θ D Δθ

Let κ = 1.53 (E = 100 GeV, ω0 = 1 eV): θ ∆θ L ∆X ∆S/S D mrad mrad m mm mm 1 1.53 10 3.83 2.59 · 10−7 46 2 3.06 10 7.65 1.04 · 10−6 92 1 1.53 5 1.91 2.59 · 10−7 46 2 3.06 5 3.83 1.04 · 10−6 92 ∆S/S ∝ κθ a) ∆X ∝ κθ·Ldipole b) D ∝ κθ·Larm c)

An ideal case: a) small angle; b) short dipole; c) long arm.

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 11 / 20

SLIDE 15

2D detector for scattered electrons?

A Transverse Polarimeter for a Linear Collider of 250 GeV e Beam Energy

Itai Ben Mordechai and Gideon Alexander (LC-M-2012-001) “... For the detection of the scattered electrons we consider only a position measurement using a Silicon pixel detector placed at a distance of 37.95 m from the Compton IP. The active dimension of the detector is 2×200 mm2. The size of the pixels cell taken is 50×400 µm2 similar to the one used in the ATLAS detector [9]. This scheme yields an approximate two dimensional resolution of 14.4×115.5 µm2 [10] with a data read-out rate of ...”

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 12 / 20

SLIDE 16

Scattering cross sections & e-beam polarisation.

Unpolarised

1 -0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 1-1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1 2 4 6 8 10 12 14 16 18 x y

Longitudinal

1 -0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 1-1
0.8
0.6
0.4
0.2

0.2 0.4 0.6 0.8 1

2.5
2
1.5
1
0.5

0.5 1 1.5 2 2.5 3 x y

Transverse

1 -0.8-0.6-0.4-0.2 0 0.2 0.4 0.6 0.8 1-1
0.8
0.6
0.4
0.2

0.2 0.4 0.6

1.5
1
0.5

0.5 1 1.5 x

In the plane of electron angles θx, θy (after scattering and bending in a dipole) cross section lies within the elliptical kinematic-bounded area.

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 13 / 20

SLIDE 17

200×100 pixels “detector”. ξζ = −0.5

X

ϑ 200 400 600 8001000 1200 1400 1600

Y

ϑ 2 − 1.5 − 1 − 0.5 − 0 0.5 1 1.5 2 5000 10000 15000 20000 25000 30000 35000 40000

HD Entries 1e+07 / ndf

2

χ 2662 / 2709

1

X 0.1649 ± 0.1313 −

2

X 0.06344 ± 1630

X

σ 0.05565 ± 21.62

1

Y 0.0001923 ± 1.63 −

2

Y 0.0001942 ± 1.63

Y

σ 0.0001082 ± 0.1045 P 0.00103 ± 0.5 − P 0.002095 ± 0.0005721 norm 772.3 ± 1.735e+06 HD Entries 1e+07 / ndf

2

χ 2662 / 2709

1

X 0.1649 ± 0.1313 −

2

X 0.06344 ± 1630

X

σ 0.05565 ± 21.62

1

Y 0.0001923 ± 1.63 −

2

Y 0.0001942 ± 1.63

Y

σ 0.0001082 ± 0.1045 P 0.00103 ± 0.5 − P 0.002095 ± 0.0005721 norm 772.3 ± 1.735e+06

= 500, P = [ 0.0, 0.0, -0.5, 0.0 ] ϑ = 3.26, κ

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 14 / 20

SLIDE 18

Fit results. ξζ = −0.5

X fit range is [200 : 1650] 200 horizontal bins means resolution σX/X ≃ 0.005/ √ 12 = 0.14%

FCN=2662.5 FROM MIGRAD STATUS=CONVERGED 257 CALLS 258 TOTAL EDM=3.9346e-08 STRATEGY=1 ERROR MATRIX UNCERTAINTY 0.8 per cent NO. NAME VALUE ERROR Remark 1 X1

1.3130e-01

1.64882e-01 ∆X1/X2 ≃ 1.0 · 10−4 2 X2 1.62998e+03 6.34381e-02 ∆X2/X2 ≃ 3.9 · 10−5 3 σX 2.16201e+01 5.56481e-02 horizontal beam size 4 Y1

1.6298e+00

1.92272e-04 vertical axis 5 Y2 1.62973e+00 1.94174e-04 vertical axis 6 σY 1.04485e-01 1.08179e-04 vertical spread 7 P

5.0003e-01

1.02951e-03 P = −0.500 ± 0.001 8 P⊥ 5.72060e-04 2.09542e-03 P⊥ = 0.000 ± 0.002 9 norm 1.73486e+06 7.72345e+02

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 15 / 20

SLIDE 19

200×100 pixels “detector”. ξζ⊥ = 0.5

X

ϑ 0 200400600800 1000 1200 1400 1600

Y

ϑ 2 − 1.5 − 1 − 0.5 − 0 0.5 1 1.5 2 5000 10000 15000 20000 25000 30000 35000 40000

HD Entries 1e+07 / ndf

2

χ 2652 / 2711

1

X 0.1596 ± 0.1629

2

X 0.07658 ± 1630

X

σ 0.06821 ± 21.62

1

Y 0.0001934 ± 1.63 −

2

Y 0.0002122 ± 1.63

Y

σ 0.0001094 ± 0.1046 P 0.0009531 ± 0.0003713 P 0.002411 ± 0.5007 norm 777.3 ± 1.707e+06 HD Entries 1e+07 / ndf

2

χ 2652 / 2711

1

X 0.1596 ± 0.1629

2

X 0.07658 ± 1630

X

σ 0.06821 ± 21.62

1

Y 0.0001934 ± 1.63 −

2

Y 0.0002122 ± 1.63

Y

σ 0.0001094 ± 0.1046 P 0.0009531 ± 0.0003713 P 0.002411 ± 0.5007 norm 777.3 ± 1.707e+06

= 500, P = [ 0.0, 0.0, 0.0, 0.5 ] ϑ = 3.26, κ

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 16 / 20

SLIDE 20

Fit results. ξζ⊥ = 0.5

X fit range is [200 : 1650] 200 horizontal bins means σX/X ≃ 0.005/ √ 12 = 0.14%

FCN=2651.75 FROM MIGRAD STATUS=CONVERGED 258 CALLS 259 TOTAL EDM=4.0963e-07 STRATEGY=1 ERROR MATRIX UNCERTAINTY 0.4 per cent NO. NAME VALUE ERROR Remark 1 X1 1.62941e-01 1.59586e-01 ∆X1/X2 ≃ 1.0 · 10−4 2 X2 1.63002e+03 7.65815e-02 ∆X2/X2 ≃ 4.7 · 10−5 3 σX 2.16220e+01 6.82096e-02 horizontal beam size 4 Y1

1.6298e+00

1.93423e-04 vertical axis 5 Y2 1.63003e+00 2.12161e-04 vertical axis 6 σY 1.04595e-01 1.09394e-04 vertical spread 7 P 3.71312e-04 9.53123e-04 P = 0.000 ± 0.001 8 P⊥ 5.00724e-01 2.41133e-03 P⊥ = 0.501 ± 0.002 9 norm 1.70728e+06 7.77293e+02

Nickolai Muchnoi IAS Program on High Energy Physics January 20, 2016 17 / 20

SLIDE 21

1

Introduction

2

Extending beam energy range?

3

Conclusion

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SLIDE 22

Conclusion

1

High energy lepton colliders require beam polarisation at least for use of resonant depolarisation approach at “low” energies.

2

With a 2D detector for scattered electrons both spin polarisation degree and direction could be measured with high accuracy.

3

Beam energy spectrometer was used at LEP and a lot of studies were made for ILC. No doubt it should be implemented on HF. A novel way for B-field integral measurements along the beam

rbit is suggested with accuracy in the range of 1 – 100 ppm.

With no additional equipment (except required for items 1,2,3) the accuracy of beam energy determination is limited by the accuracy of bending angle measurement (10 – 100 ppm) . Further studies require detailed simulations with realistic machine and scattered electrons detector parameters.

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SLIDE 23

The end

THANK YOU! Special thanks to the conference organizers for the invitation and warm welcome!

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