С.Белостоцкий сессия 2010
OLYMPUSOLYMPUS экспериментэксперимент
В. АндреевС.Белостоцкий Д.ВеретенниковГ.ГавриловА.ИзотовА.КиселевП.КравченкоА.КрившичО.МиклухоЮ.Нарышкин
+Отд.трек.дет.
Born ep CROSS SECTION AND POLARIZATIONTRANSFR
2 2 2 2E M
2
Mott
2
r2 2 2
p
e
E
2
M
G (Q ) G (Q )
G (Q ) G (
d d 1,
d d (1 )
Q,
4M
1photon polarizati
Q )
on , 0 1.1 2(1 )tan ( / 2)
pk'pk
ek 'ek
q
pJ
eJ Unpolarized cross section
С.Белостоцкий сессия 2010
Born ep CROSS SECTION AND POLARIZATIONTRANSFR
2 2 2 2E M
2
Mott
2
r2 2 2
p
e
E
2
M
G (Q ) G (Q )
G (Q ) G (
d d 1,
d d (1 )
Q,Q
4M
1, 0 1.
1 2(1 ) tan ( /
)
2)
photon polarization
pk'pk
ek 'ek
q
pJ
eJ Unpolarized cross section
Proton magnetic form factor
С.Белостоцкий сессия 2010
Born ep CROSS SECTION AND POLARIZATIONTRANSFR
2 2 2 2E M
2
Mott
2
r2 2 2
p
e
E
2
M
G (Q ) G (Q )
G (Q ) G (
d d 1,
d d (1 )
Q,Q
4M
1, 0 1.
1 2(1 ) tan ( /
)
2)
photon polarization
pk'pk
ek 'ek
q
pJ
eJ Unpolarized cross section
Proton magnetic form factor
2 2
2p E 22 2M
Untill recently it was commonly
accepted t
μ G (Q )1 at
hat
Q 10 GeV / cG (Q )
С.Белостоцкий сессия 2010
Born ep CROSS SECTION AND POLARIZATIONTRANSFR
2 2 2 2E M
2
Mott
2
r2 2 2
p
e
E
2
M
G (Q ) G (Q )
G (Q ) G (
d d 1,
d d (1 )
Q,Q
4M
1, 0 1.
1 2(1 ) tan ( /
)
2)
photon polarization
pk'pk
ek 'ek
q
pJ
eJ Unpolarized cross section
Proton magnetic form factor
иными словами, распределения заряда и магнетизма в протонесовпадают вплоть до растояний порядка 0.065 fm-1 !!
С.Белостоцкий сессия 2010
Puzzle of Proton Form Factor RatioPuzzle of Proton Form Factor Ratio
С.Белостоцкий сессия 2010
Dramatic discrepancy between Rosenbluth and recoil polarization technique
Jefferson LabMeasurement of recoil proton polarization
Puzzle of Proton Form Factor RatioPuzzle of Proton Form Factor Ratio
2 2E2 2M
'e e
ep
G (Q )
G (Q )
E EPtan( / 2)
P 2M
С.Белостоцкий сессия 2010
Contribution of Two Photon Exchange Effects Contribution of Two Photon Exchange Effects ????
+ e,p bremschtr.
С.Белостоцкий сессия 2010
p bremm
2 2 2 * 2 *ep ep Born Born 2 e bremmM M 2e M Re M 2e M M
Contribution of Two Photon Exchange Effects Contribution of Two Photon Exchange Effects ????
+ e,p bremschtr.
С.Белостоцкий сессия 2010
p bremm
2 2 2 * 2 *ep ep Born Born 2 e bremmM M 2e M Re M 2e M M
Contribution of Two Photon Exchange Effects Contribution of Two Photon Exchange Effects ????
p bremm
2 2 2 * 2 *ep ep Born Born 2 e bremmM M 2e M Re M 2e M M
2 2 2 *Born Born e bremstr p bremstr
2 2 2 *Born Born e bremstr p brems2 t
*r
*2Re(M )
Re
M 2e M 2e R e(M M )
M 2e M 2e Re(M MM ) )(
Charge asymmetry
P.G. Blunden et al.,Phys. Rev. C 72, 034612 (2005)
+ e,p bremschtr.
С.Белостоцкий сессия 2010
Model dependent
OLYMPUSEbeam=2 GeVarea
Dec.2010
С.Белостоцкий сессия 2010
The OLYMPUS ExperimentThe OLYMPUS Experiment• Electrons/positrons (100mA) in multi-GeV storage ring DORIS at
DESY, Hamburg, Germany
• Unpolarized internal hydrogen target (like HERMES) 3 x 1015 at/cm2 @ 100 mA → L = 2x1033 / (cm2s)
• Measure elastic e+/e- proton scattering to 1% precision at 2 GeV energy with ε range from 0.4 to 1 at high Q2 ~ 2-3 (GeV/c)2 using the existing Bates Large Acceptance Spectrometer Toroid
• Experiment requires switching from e+ beam to e- beam on timescale of ≤ 1 day.
• Redundant monitoring of luminosity, pressure, temperature, flow, current measurements - small-angle elastic scattering at high ε and low Q2
С.Белостоцкий сессия 2010
Создана Коллаборация OLYMPUS; Разработан TDR , в котором обозначен материальный и интелектуальный вклад участников в эксперимент; ПИЯФ и DESY подписали MoU о проведении эксперимента и об обязательствах сторон ; Эксперимент оффициально одобрен Департаментом Энергии США с гарантией финансовой поддержки; Администрация ОФВЭ поддерживает эксперимент и выделяет средства на разработку и изготовление аппаратуры, являющейся материальным вкладом института; Администрация DESY поддерживает эксперимент и содействует его проведению.
Статус эксперимента и вклад ПИЯФ
Разработана и производится трековая система монитора светимости (7 модулей пропорциональныхкамер, XUV-плоскости, шаг 1мм, всего на 2 200 каналов) для ep-elastic монитора. Проп.камеры будут использоваться в комбинации с GEM дет.ПИЯФ является отвественным за Slow Control;ПИЯФ участвует в Monte-Carlo моделировании эксперимента и в обработке и анализе экспериментальных данных.
С.Белостоцкий сессия 2010
time-of-flight
scintillators
target
GEMtrackers
12deg luminosity
GEM+MWPC
magnet coils
drift chambers
Moller/Bhabh
luminosity calorimeters
DORISbeam
OLYMPUS Experiment OLYMPUS Experiment
С.Белостоцкий сессия 2010
ep – coincidences, tracking, TOF, Δp/p
12 deg Luminosity Monitor 12 deg Luminosity Monitor
3GEMs+3MWPCs left /right symmetricallocated between toroid coilsserious difficulties with lack of space3GEMs+3MWPCs MC-tracking simulation
PCOS readout
С.Белостоцкий сессия 2010
Target System Target System
DESY integration:Will be new vacuum segment.Valves controlled by DESY vacuum group.
Pumps and internal valves will be controlled by OLYMPUS
Target Beamline Target Beamline
С.Белостоцкий сессия 2010
Test Beam Time in 2011 Test Beam Time in 2011
• TOF bars (spares from OLYMPUS)• 3 Lumi GEM detectors• 2 MWPC (prototype)• 16 lead glass detectors (Bonn)
Installation week 12-18 January
С.Белостоцкий сессия 2010
Time lines
Done-DCs wiring and tests-Toroid powering, control field mapping-TOF scint. counters revised, checked -Target cell fabricated Well on track-DORIS beam e+ /e- test 2.-2.3 GeV-IP area preparation, target installation January 2011-In construction• GEM trackers• 12 deg lumi: GEM+MWPC• Möller/Bhabha lumi calo Test run start January 2011 Detector commissioning in parking position February 2011Detector commissioning in DORIS beam August 2011 Data taking 2012
С.Белостоцкий сессия 2010
BACKUP SLIDES
Richard Milner DESY April 6, 2009 20
Projected OLYMPUS uncertaintiesProjected OLYMPUS uncertainties
Richard Milner DESY April 6, 2009 21
•Target cell installed and aligned•Cold-head installed•Pumps and controllers connected•Vacuum gauges connected
Target System Target System
R. Beck, F. Brinker DESY MAC 2010
• Shipped without wires• Completely re-wired• Currently
– electronics assembly
Wire Chambers Wire Chambers
R. Beck, F. Brinker DESY MAC 2010
• Existing radiation hard PbF2 crystals
• Assembly and testing
Moller/Bhabha Luminosity Monitor Moller/Bhabha Luminosity Monitor
R. Beck, F. Brinker DESY MAC 2010
ep ep e pM e e
Radiative Corrections & TPE graphs
p bremm
2 22 2 * *ep ep e p Born e p Born 2 e p e bremmM e e M 2e e M Re M 2e e M M
Calculable standardradiative correction
Contribution from two photon exchange diagram not taken into account in traditional analysis may be an explanation
S.Belostotski Seminar HEPD, May 05 2009
Change sign
ELASTIC ep SCATTERING AMPLITUDE ,CROSS SECTION AND POLARIZATIONTRANSFR
2
rMott p
2 2 2 2
2
2 2 2 2M
e
E E MG (Q ) G (Q ) G (Qd d 1 Q
, ,d d (1 ) 4M
1, 0 1.
1 2(1 ) tan ( / 2
) G (Q )
)photon polarization
pk'pk
ek 'ek
q
pJ
eJ
2 2' 'e e e p p pM2 E
1M e u k u k G (Q ) G (Q )e u k i q u k
q
In plane wave Born (OPE) approximation e-p scattering invariant amplitud
e
pJeJ Using M one may calculate all necessary observables:
Unpolarized cross section
Spin transfer from longitudinally polarized electron to recoil proton
2 2E2 2M
'e e
ep
G
(
E Etan(
(Q )
G (Q 2)
P
P M
P
P
Longitudinal polarization component (along recoil proton momentum)
Transverse polarizationcomponent in scattering plane
perp. to recoil proton momentum
)
/ 2)
under study
S.Belostotski Seminar HEPD, May 05 2009
Extraction of FFs from Unpolarized Elastic e-p ScatteringExtraction of FFs from Unpolarized Elastic e-p Scattering
Proton magnetic form factor
3R
2
iqx 3
3R
0
22 22
2
2D
22D
D
e e d x8
sin qRG Q
G Q
e RdR2 q
, Q qQ
0.84Ge
Q
V
GDipole parametrization
with
By far not idealbut acceptableparameterization
S.Belostotski Seminar HEPD, May 05 2009
Schedule for studies
• Operation at 2.3 GeV successfully tested in 2009/2010• Electron tests in February 2011 • First runs with test experiment in February 2011• Test runs without detector during two service weeks in April
and June 2011 ( ~ 48 hours each week )• Starting full operation with detector in August 2011• Detector commissioning and beam studies during service
weeks in September and October 2011 + parasitic running at 4.5 GeV ( w/o target )
• Possibilities for access and short tests on most Wednesdays
• 1 week commissioning in January 2012
6 shifts in 1 week
4 days
4 days
2 days
_______
12 days