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Parity Violation Experiments at SIN (as viewed by a graduate student)

Parity Violation Experiments at SIN (as viewed by a graduate student).

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Parity Violation Experiments at SIN (as viewed by a graduate student)

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  1. Parity Violation Experiments at SIN (as viewed by a graduate student) • R. Balzer1, W. Haeberli2, R. Henneck1, S. Jaccard3, S. Kistryn1, Ch. Jacquemart1,*, J. Lang1, J. Liechti1, Th. Maier1,*, R. Müller1, F. Nessi-Tedaldi1,*, W. Reichart4, T. Roser1,*, M. Simonius1, J. Smyrski1, J. Sromicki1,2, Ch. Weddigen5 • 1ETHZ, 2Wisconsin, 3SIN, 4Zürich, 5Karlsruhe • *Graduate student

  2. Parity violation in nucleon-nucleon interaction • Electro-weak part of nucleon-nucleon interaction • In one-boson exchange model: • Weak meson-nucleon coupling constants determined by standard model • Calculable due to short range of W,Z interaction • Desplanques, Donoghue and Holstein give “best value” and “range” for p,r, coupling constants: N’ N’ p,r,w P.V. N N Parity Violating Nucleon-Nucleon Potential

  3. Parity violation in nuclear scattering at ~ 45 MeV • Nuclear scattering of simple systems with less nuclear structure uncertainty • Elastic pp scattering: Az = (  1.50  0.22 )  10-7 • Elastic pa scattering: Az = (  3.34  0.93 )  10-7 • pd scattering (including part of break-up): Az = ( + 0.4  0.7 )  10-7

  4. Parity violation in low energy scattering experiment • To reach precision of better than 10-7: • Need about 1016 events, which is too many for counting individual events  integrating detectors • At low energy detection of scattered particles is preferred over transmission because the required thick target affects the beam too much • 100 atm circulating gas target to maximize luminosity and minimize thermal effects. • Scattering angle and energy cuts using target vessel walls. For pa this allowed to select only elastic scattering.

  5. Experimental layout POLARIZATIONAND INTENSITYPROFILES

  6. Facilities at SIN, now PSI Location of first phase of experiment “Haeberli Hall” Location of second phase of experiment

  7. Systematic errors • Systematic error has to be less than a few 10-8 • Good training ground for future spin physicists (needs patience and care and enthusiasm for flipping the spin!) • Basic approach: • Modulate every possible parameter artificially and measure resulting effect on Az sensitivities • Measure actual helicity correlated parameter modulation during experiment • Calculate correction/error from sensitivity and measured modulation • Systematic error sources: • Intensity modulations • Position modulations • Beam width modulations • Transverse polarization (0th,1st,2nd moment) • Energy modulations

  8. “Haeberli plot”: Comparison with PV g decays

  9. BONN SIN TRIUMF Low energy pp elastic scattering Energy dependence of p.v. partial wave amplitudes 1S0 – 3P0 and 3P2 – 1D2 are given by strong phases  only two p.v. observables

  10. TRIUMF RHIC Energy dependence of parity violation in pp total cross section • ANL measurement of p-H2O indicates fast rise of Az • Measurement of Az in pp total cross section using stored polarized beam and internal target measuring helicity-dependent beam lifetime (S. Vigdor) • Possible experiment up to 250 GeV with polarized beam at RHIC

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