compass status report
DESCRIPTION
COMPASS Status report. Fabienne KUNNE, CEA /IRFU Saclay, France On behalf of COMPASS. Physics results from hadron beam data ’’ ’’ from muon beam data 2012 run Preparation for 2015 polarized Drell -Yan. Physics from hadron beam. Rich program on hadron spectroscopy at COMPASS, - PowerPoint PPT PresentationTRANSCRIPT
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F. Kunne SPSC- June 25, 2013– 1
COMPASS Status report
Fabienne KUNNE,CEA /IRFU Saclay, France
On behalf of COMPASS
• Physics results from hadron beam data
• ’’ ’’ from muon beam data
• 2012 run• Preparation for 2015 polarized Drell-Yan
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F. Kunne SPSC- June 25, 2013– 2
Rich program on hadron spectroscopy at COMPASS,search for exotic mesons
- Diffractive resonance production- Central production
p, K, p beams - 190 GeV : large energy transfer spectrum tSpectrometer : flat acceptance, ECALs/ HCALs, RICH id. charged & neutral channelsHuge statistics
Major progress on analysisPotential for discovery of small intensity eventual new states
Physics from hadron beam
Selected results
• Diffractive processes p-p p-p+p-precoil
• Central production p p pK+K-p
• Pion polarisability p- Ni p- Ni g - (2009
Primakoff )
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F. Kunne SPSC- June 25, 2013– 3
Diffractive resonance production in p-p p-p+p-
precoil
Study 2008 data, large statistics
Partial Wave Analysis (PWA):
Step 1: In (M3p , t’) bins, 88 PW, (27 with thresholds)Impose isobar description
Step 2: M3p dependent fits on selected waves, combined fit of t’ bins (same mass, width; different background and couplings)
Extract resonance parameters
Partial waves : JPC Me [isobar] L
Isobar model
t
s
JPC-exotic mesons
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F. Kunne SPSC- June 25, 2013– 4
11 x 100 (t’,M3p) bins
Shape of mass in 2 t’ bins
t’ dependence for 2 M3 p bins
t’ ~ 0.1 GeV2/c2 t’ ~ 0.4 - 1
M3 p ~ 0.8 GeV/c2 M3 p ~ 1.6
t’
M3pM3p
t’ t’
M3p
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F. Kunne SPSC- June 25, 2013– 5
Step 1: PWA in (M, t’) bins
Intensities for 3 major waves vs M3p
t’~0.1 (GeV2/c2)
100 M3p bins
t’~0.5
1++ 0+[rp]S 2++ 1+[rp]D 2-+ 0+[f2(1270)p]S
• a1 as benchmark• Possibility of separation of resonant and non resonant content high statistics & fine binning
Peak position strength
105
37%
3 103
31 %
strength
M3p
M3p
a1(1260) a2(1320) p2(1670)
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F. Kunne SPSC- June 25, 2013– 6
Step 2 : PWA M3p dependent fit, ex: 2++
• data --- model : BW-a2 (1320) + BW-a2 (1950)+ Bkgd
• Mass dependent fits for 5 selected waves, using a model for 3p resonance + bkgd.
• 11 t’ bins• Work in progress
106log scale,
104
sum of 11 bins
sum of 11 bins
2++ 1+[rp]D
a2(1950)
a2(1320)
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F. Kunne SPSC- June 25, 2013– 7
PWA M3p dependent fit, ex: 1++
• data --- model : BW-a1 (1260) + BW-a1 (1930)+ Bckgd
106
104
sum of 11 bins (log scale)
Sum of 11 bins (linear scale)
1++ 0+[rp]S
a1(1260)
a1(1930)
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F. Kunne SPSC- June 25, 2013– 8
PWA M3p dependent fit, ex: small wave 4++
• data --- model : BW-a4 (2040) + Bckgd
<1% of total intensity, a4(2040) well established
4++ 1+[rp]G
sum of 11 bins
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F. Kunne SPSC- June 25, 2013– 9
Diffractive resonance production - conclusion
• Mass dependent PWA of 3p charged channel, Huge statistics , 50 M events, 10 times more than previous expts11 t’ bins • Well established resonances serve as benchmark
• Analysis proves the potential for establishing new small waves with firm grounds
• Spin exotic p1(1600) not shown here. High dependence on model, in particular background shape. Ongoing studies.
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F. Kunne SPSC- June 25, 2013– 10
Central production p p pK+K-p
• Preliminary fit requires strong f0(1370) signal• Strong background (non resonant contributions at low mass)
f0(1370)
f0(1500)
Double Pomeron exchange glue rich environmentProduction of non q-q meson (glueballs, hybrids) at central rapidities
pK+K-p channelSelection of central productionCut on p(pfast) >140 GeV; K id (RICH)
Mass dependent PWA f2(1270)
f2’ (1525)
rapidities
Intensity of S wave
Intensity of D wave
Phase S-D
bkgd
bkgd
+f0(1710)
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F. Kunne SPSC- June 25, 2013– 11
Pion polarisabilities - Primakoff 2009 data Polarisabilities: deviation from pointlike particle
electric (a) and magnetic (b)
At LO, Compton cross section is proportional to a p - bp
Predictions from Ch PT:
Experiments inconclusive: a p - bp = 4 -14 . 10-4 assuming (ap+bp =0)
p g p g measured via p Z p Z g
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F. Kunne SPSC- June 25, 2013– 12
Pion polarisability - result
Ratio: data/MC(pointlike)
2009 data p- Ni p- Ni g exclusive reaction• high resolution vertexing, precise calorimetry, calibrations, alignment• precise MC description of spectrometer performance,
a p - bp extracted from comparison of data to MC(pointlike)
a p - bp = (3.7 ± 1.4) x 10-4 fm3
a p = (1.9 ± 0.7)x 10-4 fm3 (assuming ap+bp =0)
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F. Kunne SPSC- June 25, 2013– 13
p Polarisability - systematic uncertainties
control measurementmResult for m compatible with expectation from simulation
Gives an upper limit on systematic uncertainty from sources common to m and p
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F. Kunne SPSC- June 25, 2013– 14
Pion polarisability – result vs world data
2012 data: 5-6 times more statistics & extended kin range
World averageCh. PT
COMPASS
ap – b p / 10-4 fm3
COMPASS result : in agreement with ChPT expectation, does not confirm other dedicated measurements
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F. Kunne SPSC- June 25, 2013– 15
Target spin
• g1p spin structure function 200GeV (2011) L
• p, K multiplicities for quark FF• Collins/ Sivers asymmetries for p / K T• 2-h asym. (p / K) + 2-h multiplicities T• Six T T-spin asymmetries (TMDs) T
• Cross section: high pT hadron g-prod.
• DVCS 2009 test run
Results from muon beam data
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F. Kunne SPSC- June 25, 2013– 16
g1p spin structure function
2011 data - First polarised DIS data at 200 GeV
NH3 target, PT85%
Vertex distribution
• Error reduction factor 3-4 vs SMC in less beam time; gain in FoM > one order of magnitude: COMPASS objective achieved.
• With slightly higher Q2, and to lower x,data complete the 2007 - 160 GeV data,
• Important to reduce systematics in low x
region of integrals, and for sea quark flavor separation
• Increase the Q2 lever arm for QCD analyses
• COMPASS 200 GeV prelim• COMPASS 160 GeV • SMC 190 GeV
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F. Kunne SPSC- June 25, 2013– 17
g1p world data
• Large set of data, extending to lower x and higher Q2 region
• Will be included in QCD global analyses
Next step:
- Bjorken Sum Rule – update
- Flavor separation, especially
Ds(x), Du(x) & Dd(x).
• COMPASS 200 GeV• COMPASS 160 GeV --- LSS QCD fit
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F. Kunne SPSC- June 25, 2013– 18
Pion and kaon multiplicities
μ+d → μ+h±XHadron production in semi inclusive DIS
2006 data analyzed. Huge statistics with 3 weeks
Full agreement with 2004 data
Fine binning in x, z, Q2
PDFs FFs
at LO
• Input to global NLO QCD analyses to extract quark FF• LO analysis, in progress within COMPASS
Goal: access to strange quark fragmentation functions
(largest contribution to uncertainty in Ds extraction from polarized SIDIS)
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F. Kunne SPSC- June 25, 2013– 19
p+ and p- multiplicities vs z in (x,y) bins
p-
p+x
preliminary
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F. Kunne SPSC- June 25, 2013– 20
K+ and K- multiplicities vs z in (x,y) bins
K+
x
K-
preliminary u s u s
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F. Kunne SPSC- June 25, 2013– 21
Kaon multiplicities & DsK
Ds from COMPASS SIDIS using 2 values for Ds
K
DsK is a key ingredient for Ds, strange quark polarization, from SIDIS
M(K+) + M(K-)
Ds from inclusive data
Small value of DsK could reconcile results
Valence region sensitive to DuK
Sea region - - -
Hint for small DsK
Work ongoing – error on multiplicities still dominated by systematics.
COMPASS PLB693(2010)227
EMC-FF
DsK
DsK / Du
K
Ds
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F. Kunne SPSC- June 25, 2013– 22
Transversity- Collins and Sivers asymmetries
qhq
2q
qhqTT
2q
Dqe
DΔqΔe
CollA
SiversCollins
qhq
2q
qhq1Tq
2q
Dqe
De
SivA
f
q transverse spin distr.Collins fragmentation function, depends on spin
Quark fragmentation function
at LO:
• T polarized target, SIDIS:
• Measure azimuthal asymmetries:
Sivers: Nucleon spin & quark transverse momentum kT
Collins: Outgoing hadron direction & quark transverse spin
m p m p h+/-
note: DTq also measured using‘’Two hadron’’ fragmentation function
TMD
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F. Kunne SPSC- June 25, 2013– 23
Collins Asymmetry on proton - p, K id.
π+
π-
preliminary
K-
K+
compatible
with π+ / π-
preliminary
~ h+ / h-
combined 2007 – 2010 results
• Agreement HERMES/COMPASS (not shown) no Q2 dependence seen (factor of ~3 inQ2)• Now also produced in bins of z and y
Correlation between outgoing hadron & quark transverse spin DTu & DTd
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F. Kunne SPSC- June 25, 2013– 24
Transversity – from Collins AsymmetryCombined analyses of HERMES, COMPASS and BELLE fragm.fct. data
Anselmino et al. arXiv: 1303.3822
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F. Kunne SPSC- June 25, 2013– 25
Sivers Asymmetry on proton - p, K id.
Correlation between nucleon spin & quark transverse momentum kT
π+
π- preliminary
K-
K+
preliminary
larger than
for π+
combined 2007 – 2010 results
• In region of overlap, agreement with HERMES, but smaller strength • Now also produced in separate bins of z and y.
~ h+ / h-
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F. Kunne SPSC- June 25, 2013– 26
2-hadron asymmetries
Another access to transversity h1
T target
• h1u & h1
d extraction• Also measured for the first time for K+K- , p+K- and K+p- pairs
q
2h
hq
2q
q
2hqT
2q
TRS Mz,Dxqe
Mz,HxqΔeA
Pf
1A
D
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F. Kunne SPSC- June 25, 2013– 27
2-h multiplicities
• First time measured in lp• Needed for pol. PDF extraction; will complete e+ e- data
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F. Kunne SPSC- June 25, 2013– 28
Six Transverse Target spin asymmetries
beyond Collins & Sivers, access TMDs
kT effects modulations in SIDIS cross-section
• Major progress in TMD measurement• Powerful tool to understand
correlations
In agreement with HERMES prelim., and with theoretical predictions
m p m p h+/-
shown as example
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F. Kunne SPSC- June 25, 2013– 29
High pT hadron photo prod. cross-section
De Florian, Pfeuffer; Schaeffer, Vogelsang, APS/123-QED
Absolute cross-section measurement 2004 data, 4 weeks
Data / theory in agreement over 4 orders of magnitude
Settles the theory framework for ΔG high pT
Ongoing: spin asymmetries ALL(pT) for same events
New: pQCD calculation with resummation ‘all orders’ (soft gluons, leading logs)
--- Resummation--- NLO--- LO
Bands= scale uncertainty
m d m’ h+/- X
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F. Kunne SPSC- June 25, 2013– 30
2009 DVCS test run data
Re-analysis of one week of data
small scale setup of DVCS m p -> m p g
- Estimation of luminosity - ECAL1/2 precise calibration using Laser/LED and calibration cell by cell using 0 mass value.
- Evaluation of p0 background with full MC (HEPGEN/exclusive and LEPTO/semi-inclusive)
p0 () in ECAL1
Data LEPTO
- Increase by 10 with 2012 Data
Background from 0 up to 50%, BUT:- very limited statistics (Data)- large uncertainty on cross-section in MC
Mgg Mgg
New features:
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F. Kunne SPSC- June 25, 2013– 31
2012 Run
• Primakoff p- Ni p- Ni g
• DVCS m+/- p m+/- g precoil
Changeover for installation of full scale DVCS setup.
Squeezed in 3 weeks, since no beam stop - cancelation of ion run.
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F. Kunne SPSC- June 25, 2013– 32
2012 Primakoff run
Goal: high statistics for polarisabilities - separate determination of ap and bp
- s dependent quadrupole polarisabilities a2 and b2
- kaon polarisabilities
2012 Running:- Long commissioning ~ 1 month- ECAL2 digital trigger commissioning, with data taking- 50 days full data taking- 15 days lost due to vacuum problems in beam line
Overall efficiency : 70 %- 88% SPS (excluding vacuum problems)- 80% COMPASS spectro + beam line magnets
Error projection: factor 5-6 + extended kinematic range
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F. Kunne SPSC- June 25, 2013– 33
2012 DVCS pilot run
GPD (Generalized Parton Distributions) by exclusive reactions DVCS, DVMP
Goal of the run: - Full scale measurement with almost full setup- Measurement with m+ and m- beams- Study background- Physics : evaluation of t-slope (transverse size of nucleon)
Detectors ready by fall 2012- initial plans were after LS1
LH2 2.5 m long targetCERN TE/CRG group
Recoil proton detector CAMERA + Gandalf FE First part of Elec.Calo ECAL0
m p→ m p g
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F. Kunne SPSC- June 25, 2013– 34
DVCS 2012 pilot run - Projection for t-slope
d DVCS/dt ~ exp-B|t| B(xB) = ½ < r2 (xB) >
Projection for ~ 2 weeks : B 5 0.7 ~ 80 DVCS events.Recall, full experiment : 40 weeks B 5 0.155 bins in xB x 5 bins in t
transverse size of the nucleon
• 2 weeks in 2012• 40 weeks > 2015
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F. Kunne SPSC- June 25, 2013– 35
COMPASS Future : Polarized Drell-Yan
Polarized Drell-Yan π- p↑ → +-X TMDs, Sivers & Boer-Mulders
Fundamental test of universality of TMDsExpect change of sign in Drell-Yan vs SIDIS
Polarized target AbsorberDipole magnet muon pairs
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F. Kunne SPSC- June 25, 2013– 36
Preparation for Polarized Drell-Yan 2015
• Modification of area in target region to include the 2m long
dedicated absorber
• Magnet repair and re-instrumentation
• Polarized target
• Move Control room from 888 (expt. Hall) to 892 (office bldg)
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2000
2300
Absorber + concrete platform
Absorber will be surrounded by 2 m of
shielding of iron-free concrete on each side.
front viewside view
2000
2000
2000 2000
2300
tungsten beam plug, alumina absorber, stainless steel shielding sandwiches
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F. Kunne SPSC- June 25, 2013– 38
Radiation Protection
Recommandations from RP group:Remove counting room from 888
- No change in classification- No need to add shielding on main wall Transitory area (no work place)
< 18 uSv/h
Unshieded area< 15 uSv/h
Barracks< 3 uSv/h
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He-pipes
Quench and Exhaust Lines
Transfer Line
Micro Wave guides
Cable trays
AbsorberControl Racks
Sketch of platform Reconfiguration of many equipments
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F. Kunne SPSC- June 25, 2013– 40
Target magnet repair and instrumentation
Magnet (major) repair CERN/ ATLAS magnet team:
- Full diagnostic on opened magnet; confirmed earlier observations of problems on trim coils (burned superconducting lines, and burned protection resistors, bad soldering, bad insulations…)
- Major work: New trim coil connections, new wiring and diodes, new heaters and sensors on cold mass, new precooling circuit, improved thermal shield cooling…
New Security and Control Systems (MSS, MCS): Built by CERN/ PH/ DT
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F. Kunne SPSC- June 25, 2013– 41
Polarized target for Drell-Yan
- 2-cell target instead of 3-cell previously.thick absorber deteriorates the resolution on the vertex reconstruction.
- new MW cavity
- New remote monitoring system
- New heat exchangers for the3He-4He dilution refrigerator
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F. Kunne SPSC- June 25, 2013– 42
Publications and conferences
Publications last 12 months
Conferences
+ 13 papers being drafted
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F. Kunne SPSC- June 25, 2013– 43
Papers being drafted
-OZI -PWA 3 pion (PRD) -Radiative widths of a2 and p2
-PWA 5 pion (PRD)-PWA of π η and π η' final states (PLB)-Pion Polarisability (PRL)
-transverse spin asymmetries beyond Collins and Sivers (all p and d) -Collins and Sivers (pions and kaons) from 2007 and 2010 (p) -2h transverse spin asymmetries (charged hadrons) from 2010 p data-Azim. hadron asym. in unpolarised deuterons
-Multiplicities pions (2006 data)-g1
p
-Spectrometer Paper (NIM)
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F. Kunne SPSC- June 25, 2013– 44
General news
MoU signed by CERN directorate, February 2013
New institutes joining• IUIC, Illinois, US
Building new large drift chambers DC5-6, to replace straw detectors
Using design and expertise from Saclay (DC4)
• Taipei
FEE for DC5-6 chamber
• Aveiro, Portugal Thick GeMs for RICH upgrade
ESRG COMPASS well cited in final report of P. NewmanNucleon structurehttps://indico.cern.ch/contributionDisplay.py?contribId=60&confId=175067 Spectroscopyhttps://indico.cern.ch/contributionDisplay.py?contribId=119&confId=175067
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45
spares
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F. Kunne SPSC- June 25, 2013– 46
Primakoff world data
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F. Kunne SPSC- June 25, 2013– 47
VM production and polarisation & OZI rule
p p p / f w p
Measure exclusive production of f and :w
Significant violation of OZI rule found, by factor of 3 to 8,
in agreement with earlier findings
Study of xF and kin. dependence to understand the scale governing
the hidden strangeness production.
Measure spin density matrices
Production mechanisms : progress in understanding the competition between processes (diffractive production of resonances, central production) by comparing spin alignments.
OZI rule predicts f suppression wrt to w.
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F. Kunne SPSC- June 25, 2013– 48
Nucleon Structure Functions
DTq(Collins)
Off diagonal: Transverse Momentum (kT) Dependent
• TMDs express correlations between spin, momentum,…• Experimentally: azimuthal modulations of outgoing
hadron in SIDIS cross section lp lp h
Nucleon Transv. Spin and quark kT
Nucleon Transv. Spin and quark Transv. Spin
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F. Kunne SPSC- June 25, 2013– 49
Semi-Inclusive Deep Inelastic Scattering
18 structure functions
14 independent azimuthal modulations
all the 14 amplitudes are been measured in COMPASS
Sivers asymmetry
Collins asymmetry
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F. Kunne SPSC- June 25, 2013– 50
Collins asymmetry on proton x > 0.032 region
charged pions (and kaons), 2010 data
comparison with HERMES results
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F. Kunne SPSC- June 25, 2013– 51
Sivers asymmetry on proton x > 0.032
charged pions (and kaons), 2010 data
comparison with HERMES results
as for h+, smaller values measured by COMPASS;same indication for K+
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3 z bins
Sivers p Sivers KCollins p Collins K
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F. Kunne SPSC- June 25, 2013– 53
3 y bins
Sivers p Sivers KCollins p Collins K
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F. Kunne SPSC- June 25, 2013– 54