Updating the laser-beam design of the ILC Compton polarimeters
A. Martens, K. Cassou, K. Dupraz, D. Nutarelli, C. Pascaud, F. ZomerLAL, Univ Paris-Sud, IN2P3/CNRS
Outline:• Introduction: Compton polarimetry• Current design of polartimeters• Impact of required error budget on design• Proposal for a new laser-systems design
Introduction: polarimetry @ ILC
Aurélien MARTENS 2
LC
C P
hys W
G a
rXiv
:18
01
.02
84
0,
Ka
rl &
Lis
t a
rXiv
:17
03
:00
21
4,
Lis
t @
ALC
W
20
15
Direct measurement at e+e- Interaction Point (IP) of longitudinal polarisation
• Several well-known x-section (total, differential, angular) measurements
Compton polarimeters constraint
useful at low statistics
Combination of Upstream and Downstream Polarimeters:
• Allows infering spin transport effects in the Beam Delivery System
• Allows determination of beam-beam effects at the e+e-IP
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Compton back-scattering polarimetry
Aurélien MARTENS 3
Used in the '90s at HERA and SLC
Measure scattered productsà e- counters (SLC/ILC)à γ calorimeter (HERA)
Barb
er e
t al.,
NIM
A329
(199
3) 7
9La
th S
LAC
PhD
thes
is (1
994)
, Woo
ds S
LAC-
PUB-
7319
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Compton polarimetry performs better compared to alternatives at higher energies
Differential count rate sensitive to transverse and longitudinal polarisation
Most sensitivity at threshold
High-order QED corrections
Aurélien MARTENS 4
QED corrections<0.1% @ 45 GeV
Dedicated studies at each ILC running energy needed ?
Denn
er&
Ditt
mai
erNu
cl. P
hys.
B 54
0 (1
999)
58,
Sw
artz
Phy
s. Re
v. D
58 0
1401
0 (1
998)
, Vel
tman
Ophy
s. Re
v. D
40 2
810
(198
9), V
eltm
anPh
ys. R
ev D
42
1856
E (1
990)
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
QED corrections about 0.5% @ 500 GeV
Processes: egàeg, egàeee, egàeggCorrections are detector dependent and energy dependent
Introduction: polarimeters @ ILC
Aurélien MARTENS 5
Bart
els e
t al.,
JIN
ST 7
P01
019
(201
2), B
ooge
rtJIN
ST 4
P10
015
(200
9),
List
@
ALCW
201
5
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
ILC design
Aurélien MARTENS 6LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Current design of laser rooms
Aurélien MARTENS 7
Bart
els
et a
l., JI
NST
7 P
0101
9 (2
012)
, Boo
gert
JIN
ST 4
P10
015
(200
9),
List
@
ALC
W 2
015
surface rooms: radiation hardness
Similar design assumed for upstream polarimeters
Not necessarily easy:Pressure, temperaturegradients
This design certainly require: • Additional thick optical windows for the laser beam transport of the large beam (few cms)• Careful compensation of pointing and position instabilities of the beam in the accelerator bay• Relatively large optics (cost)
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Current design of magnetic chicanes
Aurélien MARTENS 8
Bar
tels
et
al.,
JIN
ST 7
P0
10
19
(2
01
2),
Bo
oge
rtJI
NST
4 P
10
01
5 (
20
09
), L
ist
@A
LCW
20
15
,…
4-magnet chicane for (upstream) Compton polarimeters• No e-beam energy dependent field strength and detector acceptance
• The Interaction Point (IP) between laser and electron beams does however
Upstream (@-1800m) : horizontal chicaneLaser-beam energy: about 30µJ per pulse
Upstream
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Current design of downstream polarimeter chicane
Aurélien MARTENS 9
Ba
rte
ls e
t a
l.,
JIN
ST
7 P
01
01
9 (
20
12
), B
oo
ge
rtJI
NST
4 P
10
01
5 (
20
09
), Lis
t
@A
LC
W 2
01
5,…
6-magnet chicane
Downstream (@150m): vertical chicane ß immunity to synchrotron radiation e+e- IP
About 100mJ laser-beam pulse energy
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Current design of detectors
Aurélien MARTENS 10
Vo
rmva
lde
t a
l.,
arx
iv:1
50
9.0
31
78
, Li
st e
t a
l.,
JIN
ST 1
0 P
05
01
4 (
20
15
)
Permille control of non-linear
LED intensity thanks to
differential LED pulsesQuartz crystals: data driven gain calibration of PMs
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Source of uncertainty �P/PAsymmetry prediction (alignment, beam, backgrounds) 0.2%Detector linearity (gains, calibration system) 0.1%Jitters (beam, electronic noise) 0.05%Laser polarization 0.1%Total 0.25%
<latexit sha1_base64="t6qEC0LNXbSUFDXduDi0os3Z/Ps=">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</latexit><latexit sha1_base64="W90nAfB5j99BLiArv/71fkWFeIU=">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</latexit><latexit sha1_base64="W90nAfB5j99BLiArv/71fkWFeIU=">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</latexit><latexit sha1_base64="UUOyaTRM+0/AhHEV58xZms+jS7k=">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</latexit>
Compton polarimeters systematic uncertainties
Aurélien MARTENS 11
List
@AL
CW 2
015,
…
Account for this tight constraint in the laser design
Questions:• Does the current laser design seem compliant with this request ?• Strategy to control laser-beam polarisation at this precision ?
Review the laser design for the upstreamcompton polarimeter
Challenging per-mille ellipsometry
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Laser-beam ellipsometry
Aurélien MARTENS 12
Poirs
onet
al.
Appl
ied
Opt
ics 3
4 68
06 (1
995)
, Bris
son
JINST
5 P
0600
6 (2
010)
, Zo
mer
HDR
(200
3), J
acqu
etHD
R (2
009)
, Bau
dran
dPh
D th
esis
(200
7)
LASER GLAN Beamtransport HB
S
Wollaston
PDe
QWP
QWP2
PDi
PD1PD2
Minimal optical components to generate (pure) circular laser beam polarisation
Beamtransport
IP
Extremely difficult to remove wrong polarisation <0.1%
Residual wrong polarisation vs tilt angle
About 1 per mille wrong polarisation
Fine modeling of beam transport is required
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Laser-beam ellipsometry
Aurélien MARTENS 13
Briss
on JI
NST
5 P
0600
6 (2
010)
, Zom
erHD
R (2
003)
, Jac
quet
HDR
(200
9),
Baud
rand
PhD
thes
is (2
007)
LASER GLAN Beamtransport HB
S
Wollaston
PDe
QWP
QWP2
PDi
PD1PD2
Beamtransport
IP
• Minimize amount of material seen by the laser-beam by • use of reflective optics• Reducing optical path length
• Calibrate effects on polarisation from laser-beam transport
Example of fit of PD intensities versus QWP angle• Large number of parameters (misalignements,
thickness defaults,…)• Fraction of per-mille precision
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Laser-beam ellipsometry
Aurélien MARTENS 14
Briss
on JI
NST
5 P0
6006
(201
0), Z
omer
HDR
(200
3), J
acqu
etHD
R (2
009)
, Ba
udra
ndPh
D th
esis
(200
7)
LASER GLAN Beamtransport HB
S Wollaston
PDe
QWP
QWP2
PDi
PD1PD2
Thermalized electronics
Beamtransport
IP
• Polarisation independent Holographic Beam Sampler• Careful suppression of laser intensity fluctuations• Use of balanced photodiodes and differential electronics
Example of measurements @ HERA
• More frequent measurements ?• Modulation of circular polarisation to
avoid DC fluctuations ?
Temporal fluctuations à precision 0.3% (HERA)
R&D required to reach 0.1%
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Upstream Laser design: example of industrial laser
Aurélien MARTENS 15
Demanding industrial sector: routinely operating systems
Ultra compact ! à integrate close to Compton IP ?
http
://w
ww.
ampl
itude
-sys
tem
es.co
m, L
aser
-Tec
hnik
Jour
nal (
2/20
16) 5
6
Concurrent designs certainly exist à detailed study of the market is required
Viable for 30µJ/pulse in redAllow for continuous ellipsometry at 1.8 MHz J
100W in red à 50w in green
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Aurélien MARTENS 16
http
://w
ww.
ampl
itude
-sys
tem
es.co
m, L
aser
-Tec
hnik
Jour
nal (
2/20
16) 5
6 Upstream Laser design: example of industrial laser
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Downstream Laser design: example of industrial laser
Aurélien MARTENS 17
Dur
and
et a
l, Pr
oc. S
PIE
1051
1, S
olid
Sta
te L
aser
s XX
VII:
Tech
nolo
gyan
d D
evic
es, 1
0511
1B (2
018)
, h
ttp
s://
ww
w.t
rum
pf-
scie
nti
fic-
lase
rs.c
om
/en
_IN
T/p
rod
uct
s/d
ira
-se
rie
s/
For instance DIRA can deliver 100mJ @ 2kHz
Initial requirement : 100mJ @ 5Hz, commercial laser systems exist
Question: • is it possible to gain in polarimeter performances with existing more powerful laser
• Would it be useful for physics ?
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Proposed laser room specifications
Aurélien MARTENS 18
EDM
S do
cum
ent
D*0
1154
075,
ILC-
CR-0
015
3m Office, storagefor occasionalworks
Laser room <1°C stability>ISO7 quality
tow
ards
com
pton
IP
TBD
but
abo
ut 1
0m (U
pstr
eam
)La
rger
for
Dow
nstr
eam
IP
from
com
pton
IP
4.2m
Laser rooms
Compton polarimeter IPs
2 mLCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Proposed laser-beam transport specifications
Aurélien MARTENS 19
Laser room Alternatively: place diagsaround here
Use of lens not ideal
Prefer reflective optics& careful alignement
EDM
S do
cum
ent
D*0
1154
075,
ILC-
CR-0
015
ideally ground transport à certainly not possible à requires dedicated studies
Primary vacuum is enough
(for upstream)
IP
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018
Conclusion
Aurélien MARTENS 20
Laser beam systems for ILC polarimeters is being reviewed
Optimisation and control of the laser-beam polarisation at the per-mille level is required
• Seem possible to locate laser-room close to compton IPs• Industrial compact and robust lasers that meet requirements are available• First preliminary specifications for optical rooms, laser beam transport drawn• Interfaces to be discussed
• Extremely difficult to cancel residual wrong polarisation at 1‰• Require excellent modelling of the optical system as a whole• Require R&D on detection system, modulation technique ?• Compromise between fast continuous ellipsometry (using e-beam off time too) and
total laser beam power manageable
Actual needs impact final laser-beam system designà Especially true for the downstream polarimeter
Review of laser-beam design, some preliminary statements drawn
R&D is required on precise and robust laser-beam ellipsometry
LCWS 2018 – MDI, Arlington, TX, USA, 23/10/2018