1. COMPASS muon programme
Alain Magnon
DAPNIA/SPhN (CEA Saclay)
On behalf of the COMPASS Collaboration
A.Magnon
COMPASS week, PRAGUE August 1st

2. COMPASS week, PRAGUE August 1st-5 2005
Content
Highlights about results, upgrades, prospects,
- SPSC Villars meeting Sept 2004
- SPSC71 meeting 3 May 2005 (G. Mallot)
- SPSC72 meeting 5 July 2005
- Talks by Paolo P., Sonia H. & Alex K. (section 4)
Vadim A. (section 5)
2006 & beyond ?
A.Magnon
COMPASS week, PRAGUE August 1st

3. Villars 2004 Report on the SPSC Villars Meeting September 22-28 2004
John Dainton
University of Liverpool, GB
(on behalf of the SPSC)
A.Magnon
COMPASS week, PRAGUE August 1st

4. Villars 2004 Framework Machines and Beams Heavy Ions Neutrinos
Soft and Hard Protons
Antiproton Physics
Flavour Physics
Other Topics
Summary
Report on the SPSC Villars Meeting
September
John Dainton
University of Liverpool, GB
(on behalf of the SPSC)
COMPASS
Report on the SPSC Villars meeting by John Dainton, University of Liverpool
(CERN-SPSC SPSC-M-730 February 28th 2005, available on Web)
A.Magnon
COMPASS week, PRAGUE August 1st

5. COMPASS Collaboration
Bielefeld, Bochum, Bonn (ISKP, PI), Burdwan and Calcutta,
CERN, Dubna (LPP, LNP), Erlangen, Freiburg, Lisbon,
Mainz, Moscow (INR, LPI, MSU), Munich-LMU,
Munich-TU, Nagoya, Prague (CU, CUT, TUL), Protvino,
Saclay, Tel Aviv, Torino (Univ., INFN), Trieste (Univ.,INFN), Warsaw (SINS), Warsaw (TU)
More than 220 physicists from 28 Institutes
A.Magnon
COMPASS week, PRAGUE August 1st

6. Hadron structure and spectroscopy
Physics programme
Stephan Paul talk
Hadron structure and spectroscopy
Muon beam programme
Quarks and gluon polarisation
in polarised (longitudinal) nucleons
Transverse spin distribution
Lambda polarisation
Diffractive vector-meson production
Hadron beam programme
Polarisibility of pions and kaons
(Primakoff reaction)
Exotics q-states, glue balls
Semi-leptonic decays of charmed baryons
Double charmed hadrons
GPDs (DVCS, HEMP)
- under consideration -
Nicole d’Hose talk
A.Magnon
COMPASS week, PRAGUE August 1st

7. COMPASS week, PRAGUE August 1st-5 2005
Spectrometer > 2004
trigger-hodoscopes
DW45
straws
SM2 dipole
Muon-filter2,MW2
RICH_1
HCAL1
Gem_11
SM1 dipole
ECAL2,HCAL2
Polarised Target
MWPC Gems Scifi
SPS 160 GeV
2.108m/spill
Muon-filter1,MW1
Veto
straws,MWPC,Gems,SciFi
Gems,SciFi,DCs,straws
Silicon
SciFi
Micromegas,DC,SciFi
A.Magnon
COMPASS week, PRAGUE August 1st

8. COMPASS week, PRAGUE August 1st-5 2005
COMPASS objectives
Original programme set for about 5 years (1) of running
at 150 days/year with 14.4s supercyle and eSPS = 80%.
i.e. 7.2  105 spills/year
i.e PoT/year (2  108 m/spill)
(1) HMC (4 years) - CHEOPS (2 years)
A.Magnon
COMPASS week, PRAGUE August 1st

9. COMPASS week, PRAGUE August 1st-5 2005
Data taking 2002 – 2004
Beam (1) days 90d d
єSPS+BL (2)
Preparation ~30d d d
єSpectro(3)
Data taking (4) d d d
muon (L/T) d/11d 30d/9d 47d/14d
2004
19d 4d
15d
hadron
(1) Scheduled beam excluding MDs (4) L/T Longitudinal/Transverse sharing ~ 80/20
(2) Inefficiency from SPS, beam line, etc
(3) ~ 0.90 additional due to time needed to rotate spin and calibrate spectrometer
A.Magnon
COMPASS week, PRAGUE August 1st

10. COMPASS week, PRAGUE August 1st-5 2005
Data taking
muon: > 11.6  105 spills
request: 7.2  105 spills/year  2.5 (proposal-year)
We got ~ 1.6 (proposal-year)
Pilot hadron run: > ~ 0.7  105 spills
A.Magnon
COMPASS week, PRAGUE August 1st

11. COMPASS week, PRAGUE August 1st-5 2005
Physics results
Highlights (SPSC71 status report) :
- g1
- transversity
- L polarisation
-DG/G from high pT hadron pairs
-DG/G from open-charm
- more …
A.Magnon
COMPASS week, PRAGUE August 1st

12. COMPASS week, PRAGUE August 1st-5 2005
g1 of the deuteron
data
most precise measurement for < x < PLB 612 (2005) 154
new NLO QCD fit, precision of a0 improves factor 2 (<Q2> = 4 GeV2)
A.Magnon
COMPASS week, PRAGUE August 1st

13. COMPASS week, PRAGUE August 1st-5 2005
Towards transversity
single transverse-spin asymmetries (2002 data)
- Collins: related to transverse quark distributions
- Sivers : related to intrinsic kT h+ h-
Collins
PRL 94, (2005)
Sivers
A.Magnon
COMPASS week, PRAGUE August 1st

14. COMPASS week, PRAGUE August 1st-5 2005
Quark polarimeters
all asymmetries compatible with zero
measure product of chiral-odd FF and transverse-PDF
- is the analysing power of Collins FF small?
or are the transverse parton distributions small?
(proton-neutron cancellation in deuteron ?)
try other polarimeters
- interference FF of two hadrons
- lambda polarisation
A.Magnon
COMPASS week, PRAGUE August 1st

15. Theoretical work on Sivers SSA
“Extracting the Sivers function from polarized SIDIS data and making predictions”
- Phenomelogical model whose parameters are constrained by HERMES proton measurements.
- COMPASS 2002 preliminary results for Sivers effect are in agreement with the model.
Are now COMPASS data included in the fit?
M. Anselmino et al. hep-ph/057181
(including HERMES Prel. Results shown at DIS05)
A.Magnon
COMPASS week, PRAGUE August 1st

16. Theoretical work on Sivers SSA
“Predictions of Sivers
asymmetries on a proton
target”
M. Anselmino et al. hep-ph/057181
A.Magnon
COMPASS week, PRAGUE August 1st

17. Expected accuracy for Collins asymmetries
2002
2002-4
2006
A.Magnon
COMPASS week, PRAGUE August 1st

18. ΔG/G from Photon-Gluon Fusion
Strategies to suppress background:
1) Open charm production:
q = c unique, no background
charm fragmentation, 1.2 D0 per event
D0 -> K- π+ (BR 4%), D*+(~20%) -> D0 π+
2) High-pT hadron pair production: q=u,d,s background from
non PGF events & resolved g
pQCD scale set by:
1) ŝ > 4mc2 or
2) ŝ > (pt1+pt2)2
LOW STAT.
HIGH STAT.
Photon Gluon Fusion
Needed since Q2 ~ 0
A.Magnon
COMPASS week, PRAGUE August 1st

19. ΔG/G from high-pT hadron pair
e, m h1 h2 N
Photon Gluon Fusion
Leading order Process
QCD-Compton
measured
aLL : calculable partonic asymmetries
R : Monte-Carlo (Lepto/Phytia depending on Q2)
A.Magnon
COMPASS week, PRAGUE August 1st

20. COMPASS week, PRAGUE August 1st-5 2005
high-pT hadron pairs
Q2<1GeV2 Q2>1GeV2
Q2 < 1GeV evts
Q2 > 1GeV evts
2002 and 2003 data
- pT,1, pT,2 > 0.7 GeV, p2T,1 + p2T,2 > 2.5 GeV2,
- for statistical reasons use A|| / D
- D depolarisation factor,
- exact formula used in analysis
A.Magnon
COMPASS week, PRAGUE August 1st

21. high-pT hadron pairs: Q2<1GeV2
more difficult than large Q2
contributions from resolved photons
- spin dependent structure of the photon
perturbative part calculable
non-perturbative part:
- min/max VMD scenarios (Glück, Reya, Sieg)
- tuning of intrinsic kT partons in the photon
nucleon parameters
- tuning of fragmentation functions
- tuning of intrinsic kT in nucleon
A.Magnon
COMPASS week, PRAGUE August 1st

22. Gluon polarisation, high pT pairs
Q2>1GeV2 :
data
Q2<1GeV2:
A.Magnon
COMPASS week, PRAGUE August 1st

23. COMPASS week, PRAGUE August 1st-5 2005
Gluon polarisation
G = 2.48
G = 0.62
G = 0.16
GRSV2000
NLO fits to g1
m2 = 3 Gev2
ΔG/G (xg ≈ 0.1) is small
DG>1 disfavoured
A.Magnon
COMPASS week, PRAGUE August 1st

24. Open charm: D’s from D*’s
requiring the slow pion in D* → D πs→ K π πs
D0 → K π π0
A.Magnon
COMPASS week, PRAGUE August 1st

25. Gluon polarisation, D0 & D* events
data
DG/G = /- 0.73
<xg> = /- 0.08
A.Magnon
COMPASS week, PRAGUE August 1st

26. COMPASS week, PRAGUE August 1st-5 2005
Gluon polarisation
G = 2.48
G = 0.62
G = 0.16
GRSV2000
NLO fits to g1
A.Magnon
COMPASS week, PRAGUE August 1st

27. Figure of Merit for open charm
FoM
2002 – > 2006
FoM(DG/G)
s(DG/G)=1/FoM1/2
We work very hard to increase FoM
A.Magnon
COMPASS week, PRAGUE August 1st

28. Figure of Merit for open charm
FoM increase in 2006 (with upgrades):
New COMPASS magnet: 1.3
Rich upgrade: 1.5
Ecal: 1.2
K below threshold: 1.1
100 days of beam: 1.3 -> (~ .9)
total: 3.4 -> (~2.4)
A.Magnon
COMPASS week, PRAGUE August 1st

29. Large Angle Spectrometer 2002-3-4-6
DC1 DC DC4 Straws
Initial lay-out
end 2002
downstream
of SM2
~ 200 mrd
COMPASS PT solenoid
Modified
.....
~ 70 mrd
SMC solenoid
Straws: / 1/2
DCs: 3
A.Magnon
COMPASS week, PRAGUE August 1st

30. COMPASS Oxford Danfysik magnet
OD magnet presently tested and
instrumented in Saclay
Some delays ...
Magnet will be delivered to CERN
in November
A.Magnon
COMPASS week, PRAGUE August 1st

31. COMPASS week, PRAGUE August 1st-5 2005
COMPASS OD magnet
1st attempt to get uniform field (24.06): encouraging
100 ppm
Request is ≤ 100 ppm
A.Magnon
COMPASS week, PRAGUE August 1st

32. COMPASS week, PRAGUE August 1st-5 2005
RICH (PDs) upgrade in 2006
5 m
6 m
3 m
Photon
Detectors:
CsI MWPC
mirror
wall
vessel
radiator:
C4F10
A.Magnon
COMPASS week, PRAGUE August 1st

33. COMPASS week, PRAGUE August 1st-5 2005
RICH upgrade in 2006
central region ‘maPMT’:
multi-anode PMTs
lens system
MAD4 preamp
F1 TDCs, excellent time resolution
outer region ‘APV’:
keep CsI photodetector
new readout based on APV chips
good timing resolution
‘no’ DAQ dead time
beam
A.Magnon
COMPASS week, PRAGUE August 1st

34. COMPASS week, PRAGUE August 1st-5 2005
RICH maPMT
elements tested in T11 beam
approved by INFN in April, design of
optics finished, PMs ordered (600)
delivery schedule Q till Jan 2006
ready spring 2006
Trieste, Turin + Bonn, Erlangen, Freiburg, Lisbon, Mainz, Prague (2)
A.Magnon
COMPASS week, PRAGUE August 1st

35. COMPASS week, PRAGUE August 1st-5 2005
APV RICH project
BORA CONNECTOR
+3.7V, -3.7V, GND
10 PIN HE10CONNECTOR
+5V, -5V, GND
10 PIN HE14CONNECTOR
4 Differential ADC Outputs
RJ45 CONNECTOR
CLK, TRIGGER, I2C
+ & V
Regulator
POWER_MUX ( STRAPS )
& +/- 3.3V Regulators
+/- 5V or +/-3.7V
x 4 Fanout
+/- 3.3 or 3.7 V
4 differential amplifiers J8 J7 J6 J5 J4 J3 J2 J1 J0
APV3
APV2
APV1
APV0 48 12 36 24
Figure 1 : Block-diagram of the new board
dR, cm
Trigger time x25ns
R/O successfully tested during 2004 on the Rich
installation and test Q1 /06
Design based on GEM & Si FEE
Provides signal timing
accuracy <200ns
TU-Munich, Saclay
A.Magnon
COMPASS week, PRAGUE August 1st

36. COMPASS week, PRAGUE August 1st-5 2005
Large drift chamber DC4
Chamber under construction by Saclay
frames delivered
assembly and test Q4/05-Q1/06
operational April 2006
A.Magnon
COMPASS week, PRAGUE August 1st

37. COMPASS week, PRAGUE August 1st-5 2005
ECAL1
Plan to equip entire ECAL1 for 2006 (Protvino)
Also beneficial for open-
charm
D0 → K π π0
D*0 → D0 π0s
A.Magnon
COMPASS week, PRAGUE August 1st

38. COMPASS week, PRAGUE August 1st-5 2005
SPS in 2006
Schedule prepared by SPS Coordinator
& proposed by SPSC
COMPASS = 3440 h–> 142 days
COMPASS – (2004)= 3120 h–> 130 days
110(m) 20(h)
A.Magnon
COMPASS week, PRAGUE August 1st

39. COMPASS week, PRAGUE August 1st-5 2005
SPS in 2006
Schedule was not accepted by CERN RB
New (draft) schedule:
COMPASS – 2006’
2728 h–> 113 days (not 142 d)
restart of SPS etc …
єSPS+BL ~ 0.7 or lower
~ 0.5 proposal year
A.Magnon
COMPASS week, PRAGUE August 1st

40. COMPASS week, PRAGUE August 1st-5 2005
Conclusion
muon programme was for ~2.5 years (SPS proposal-years)
with 1.6 year of running, important physics results were
obtained, also :
- 3 physics papers (g1d, Collins/Sivers asym., penta-q search)
- DG/G with remarkable precision from high pT low Q2
- s(DG/G) from D0 (0.73 -> 0.43 with 2004)
A.Magnon
COMPASS week, PRAGUE August 1st

41. COMPASS week, PRAGUE August 1st-5 2005
Conclusion
Ambitious objective for 2006
Complete proposed muon programme
- get error on DG/G from charm close to error of proposal,
- run both with deuteron & proton target
1/ successful equipment upgrades
2/ sufficient beam allocation from SPS (?)
A.Magnon
COMPASS week, PRAGUE August 1st

42. COMPASS week, PRAGUE August 1st-5 2005
Additional slides
A.Magnon
COMPASS week, PRAGUE August 1st

43. COMPASS week, PRAGUE August 1st-5 2005
s(h1d,h1p) vs acceptance
COMPASS magnet
SMC magnet
A.Magnon
COMPASS week, PRAGUE August 1st

44. Resolved photon contributions
PYTHIA
e.g.:
qq’→ qq’
A.Magnon
COMPASS week, PRAGUE August 1st

45. COMPASS week, PRAGUE August 1st-5 2005
Example: kT tuning
nucleon
photon
systematic error
- determined using 15 independent MC simulations
- exploring the parameter space
in kT of nucleon and photon
fragmentation functions
parton shower on/off,
renormalisation scale
A.Magnon
COMPASS week, PRAGUE August 1st

46. COMPASS week, PRAGUE August 1st-5 2005
Data versus MC
excellent to good
agreement for all
kinematics variables
let’s get
A.Magnon
COMPASS week, PRAGUE August 1st

47. COMPASS week, PRAGUE August 1st-5 2005
Data versus MC
excellent to good agreement
for all kinematics variables
let’s get
A.Magnon
COMPASS week, PRAGUE August 1st

48. high-pT hadron pairs: Q2>1GeV2
xBj < 0.05, can neglect QCD Compton and LO
LEPTO tuning à la SMC high-pT pT x p
A.Magnon
COMPASS week, PRAGUE August 1st

49. COMPASS week, PRAGUE August 1st-5 2005
Open charm: MC studies pT z y
AROMA Monte Carlo, PGF only
background subtracted 2003 data (side bands)
D’s indeed from PGF ? Data understood?
good agreement data / MC
hard z-distribution
A.Magnon
COMPASS week, PRAGUE August 1st

50. COMPASS week, PRAGUE August 1st-5 2005
Open charm: MC studies
aLL from one hadron from PGF reconstructed
Correlation of generated and reconstructed aLL
Analysis uses event weighting with aLL deduced from hadron kinematic variables
A.Magnon
COMPASS week, PRAGUE August 1st

51. COMPASS week, PRAGUE August 1st-5 2005
RICH upgrade in 2006
A.Magnon
COMPASS week, PRAGUE August 1st