10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 1 Novel Technique to Measure the Polarizability of the Nucleon* Olena Yevetska Institut für Kernphysik, TU Darmstadt SFB 634 • Motivation • Experimental Setup • Experiments • Results • Summary and Outlook *Supported by the DFG within SFB 634
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Novel Technique to Measure the Polarizability of the Nucleon*
Novel Technique to Measure the Polarizability of the Nucleon*. Olena Yevetska Institut für Kernphysik, TU Darmstadt. Motivation Experimental Setup Experiments Results Summary and Outlook. SFB 634. *Supported by the DFG within SFB 634. E. B. Motivation. a , b - electric and - PowerPoint PPT Presentation
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10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 1
Novel Technique to Measure the Polarizability of the Nucleon*
Olena YevetskaInstitut für Kernphysik, TU Darmstadt
SFB 634
• Motivation
• Experimental Setup
• Experiments
• Results
• Summary and Outlook
*Supported by the DFG within SFB 634
10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 2
Motivation
, - electric and magnetic
polarizabilitiesu
d
u
u
d
u E
Bd = E = B
describe the response of the nucleon internal structure to applied electric and magnetic fields
3410)3.15.09.11( fmp 3410)3.07.02.1( fmp
V. Olmos de Leon et al., Eur. Phys. J. 10 (2001) 207
Goal: better accuracy of these constants
3410)4.28.8( fmn
3410)4.25.6( fmn
M. Lundin et al., Phys. Rev. Lett. 90 (2003) 192501
10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 3
Motivation
Low energy Compton scattering ( E < 140 MeV)
Low Energy Theorem:
intPod
),E(d
Powell cross section for the point like proton with anomalous magnetic moment
Structure term
)E( 40 Terms of higher order structure constants
V. Petrun‘kin et al., Sov. J. Part. Nucl. 12 (1981) 278
)(0),(),( 4
Ed
Ed
d
Ed
Poin
tPoint
2´
22 )cos1(2
)cos1(2 E
~
+ -
10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 4
Experiment with Compton Scattering
previous now E´
p,dEp,d
´
DetectorDetector
Target
1023 protons/cm21022 protons/cm2
E,
Liquid H/D-target Active high pressure H/D-target
• high luminosity: 106 /MeV/s 109 /MeV/s
• background suppression:redundancy of kinematic values
• Bremsstrahlung spectrum has to be known
E´
´
Ep = 0.4 – 8 MeV
10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 5
S-DALINAC
5 m
Accelerator Hall Experimental Hall
( ́ ) & - Experiments (n)
Compton Scattering on Nucleon
(e,e´x) & 180°- Experiments at QCLAM Spectrometer
(e,e´) - Experiments at Lintott Spectrometer
( ´x)- Experiments at NEPTUN Tagger
Design Parameters
Maximum energy: 130 MeV
Energy spread : 10-4
Maximum current: 20 A
Material: Niobium
Temperature: 2K
10.03.2008 | Institut für Kernphysik | TU Darmstadt | Olena Yevetska | 6