First Measurement Using Elliptically Polarized Photons of the Double-Polarization Observable E for γ p → p π 0 and γ p → n π +

Afzal, F.; Spieker, K.; Hurck, P.; Abt, S.; Achenbach, P.; Adlarson, P.; Ahmed, Z.; Akondi, C. S.; Annand, J. R. M.; Arends, H. J.; Bashkanov, M.; Beck, R.; Biroth, M.; Borisov, N.; Braghieri, A.; Briscoe, W. J.; Cividini, F.; Collicott, C.; Costanza, S.; Denig, A.; Dieterle, M.; Downie, E. J.; Drexler, P.; Fegan, S.; Gardner, S.; Ghosal, D.; Glazier, D. I.; Gorodnov, I.; Gradl, W.; Gurevich, D.; Heijkenskjöld, L.; Hornidge, D.; Huber, G. M.; Kashevarov, V. L.; Kay, S. J. D.; Korolija, M.; Krusche, B.; Lazarev, A.; Livingston, K.; Lutterer, S.; MacGregor, I. J. D.; Macrae, R. G.; Manley, D. M.; Martel, P. P.; Miskimen, R.; Mocanu, M.; Mornacchi, E.; Mullen, C.; Neganov, A.; Neiser, A.; Oberle, M.; Ostrick, M.; Otte, P. B.; Paudyal, D.; Pedroni, P.; Powell, A.; Reicherz, G.; Rostomyan, T.; Sfienti, C.; Sokhoyan, V.; Steffen, O.; Strakovsky, I. I.; Strub, T.; Supek, I.; Thiel, A.; Thiel, M.; Thomas, A.; Usov, Yu. A.; Wagner, S.; Walford, N. K.; Watts, D. P.; Werthmüller, D.; Wettig, J.; Witthauer, L.; Wolfes, M.; Zachariou, N.

doi:10.1103/PhysRevLett.132.121902

Title: First Measurement Using Elliptically Polarized Photons of the Double-Polarization Observable $E$ for $γ p \to p π^{0}$ and $γ p \to n π^{+}$

Journal Article · 19 March 2024 · Physical Review Letters

DOI: https://doi.org/10.1103/PhysRevLett.132.121902 · OSTI ID:2325098

; Spieker, K.; Hurck, P.; Abt, S.; Achenbach, P.; Adlarson, P.; Ahmed, Z.; Akondi, C. S.; Annand, J. R. M.; Arends, H. J.; Bashkanov, M.; Beck, R.; Biroth, M.; Borisov, N.; Braghieri, A.; Briscoe, W. J.; Cividini, F.; Collicott, C.; Costanza, S.; Denig, A. more »

We report the measurement of the helicity asymmetry $E$ for the $p π^{0}$ and $n π^{+}$ final states using, for the first time, an elliptically polarized photon beam in combination with a longitudinally polarized target at the Crystal Ball experiment at MAMI. The results agree very well with data that were taken with a circularly polarized photon beam, showing that it is possible to simultaneously measure polarization observables that require linearly (e.g., $G$ ) and circularly polarized photons (e.g., $E$ ) and a longitudinally polarized target. The new data cover a photon energy range 270–1400 MeV for the $p π^{0}$ final state (230–842 MeV for the $n π^{+}$ final state) and the full range of pion polar angles, $θ$ , providing the most precise measurement of the observable $E$ . A moment analysis gives a clear observation of the $p η$ cusp in the $p π^{0}$ final state. Published by the American Physical Society 2024

View Journal Article

Cite

Export

Save

Sponsoring Organization:: USDOE

Grant/Contract Number:: FG02-99-ER41110; FG02-88ER40415; FG02-01-ER41194; SC0014323; SC0016583

OSTI ID:: 2325098

Journal Information:: Physical Review Letters, Journal Name: Physical Review Letters Vol. 132 Journal Issue: 12; ISSN 0031-9007

Publisher:: American Physical SocietyCopyright Statement

Country of Publication:: United States

Language:: English

References (45)

Quark models of baryon masses and decays Capstick, S. Progress in Particle and Nuclear Physics, Vol. 45 https://doi.org/10.1016/S0146-6410(00)00109-5	journal	January 2000
P -wave baryons in the quark model Isgur, Nathan; Karl, Gabriel Physical Review D, Vol. 18, Issue 11 https://doi.org/10.1103/PhysRevD.18.4187	journal	December 1978
Determining the dominant partial wave contributions from angular distributions of single- and double-polarization observables in pseudoscalar meson photoproduction Wunderlich, Y.; Afzal, F.; Thiel, A. The European Physical Journal A, Vol. 53, Issue 5 https://doi.org/10.1140/epja/i2017-12255-0	journal	May 2017
Polarised targets for 4π detectors at MAMI Thomas, A. The European Physical Journal Special Topics, Vol. 198, Issue 1 https://doi.org/10.1140/epjst/e2011-01489-8	journal	September 2011
Measurement of π 0 photoproduction on the proton at MAMI C Adlarson, P.; Afzal, F.; Akondi, C. S. Physical Review C, Vol. 92, Issue 2 https://doi.org/10.1103/PhysRevC.92.024617	journal	August 2015
CryPTA2022, Status Report from this year's annual Meeting Dutz, Hartmut Proceedings of 19th Workshop on Polarized Sources, Targets and Polarimetry — PoS(PSTP2022) https://doi.org/10.22323/1.433.0021	conference	March 2023
Excited state baryon spectroscopy from lattice QCD Edwards, Robert G.; Dudek, Jozef J.; Richards, David G. Physical Review D, Vol. 84, Issue 7 https://doi.org/10.1103/PhysRevD.84.074508	journal	October 2011
The impact of $K^{+}\Lambda$ K + Λ photoproduction on the resonance spectrum Rönchen, D.; Döring, M.; Meißner, U. -G. The European Physical Journal A, Vol. 54, Issue 6 https://doi.org/10.1140/epja/i2018-12541-3	journal	June 2018
Quasifree photoproduction of η mesons off protons and neutrons Werthmüller, D.; Witthauer, L.; Keshelashvili, I. Physical Review C, Vol. 90, Issue 1 https://doi.org/10.1103/PhysRevC.90.015205	journal	July 2014
Proton-η′ interactions at threshold Anisovich, A. V.; Burkert, V.; Dugger, M. Physics Letters B, Vol. 785 https://doi.org/10.1016/j.physletb.2018.06.034	journal	October 2018
Observation of the pη′ Cusp in the New Precise Beam Asymmetry Σ Data for γp→pη Afzal, F.; Wunderlich, Y.; Anisovich, A. V. Physical Review Letters, Vol. 125, Issue 15 https://doi.org/10.1103/PhysRevLett.125.152002	journal	October 2020
Relevance of complex branch points for partial wave analysis Ceci, S.; Döring, M.; Hanhart, C. Physical Review C, Vol. 84, Issue 1 https://doi.org/10.1103/PhysRevC.84.015205	journal	July 2011
Completeness rules for spin observables in pseudoscalar meson photoproduction Chiang, Wen-Tai; Tabakin, Frank Physical Review C, Vol. 55, Issue 4 https://doi.org/10.1103/PhysRevC.55.2054	journal	April 1997
The BaF/sub 2/ photon spectrometer TAPS Novotny, R. IEEE Transactions on Nuclear Science, Vol. 38, Issue 2 https://doi.org/10.1109/23.289329	journal	April 1991
The impact of new polarization data from Bonn, Mainz and Jefferson Laboratory on $\gamma p \rightarrow \pi N$ multipoles Anisovich, A. V.; Beck, R.; Döring, M. The European Physical Journal A, Vol. 52, Issue 9 https://doi.org/10.1140/epja/i2016-16284-9	journal	September 2016
Well-Established Nucleon Resonances Revisited by Double-Polarization Measurements Thiel, A.; Anisovich, A. V.; Bayadilov, D. Physical Review Letters, Vol. 109, Issue 10 https://doi.org/10.1103/PhysRevLett.109.102001	journal	September 2012
The 1.5GeV harmonic double-sided microtron at Mainz University Kaiser, K. -H.; Aulenbacher, K.; Chubarov, O. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 593, Issue 3 https://doi.org/10.1016/j.nima.2008.05.018	journal	August 2008
Measurement of the helicity asymmetry $${\mathbb {E}}$$ for the $$\vec {\gamma }\vec {p} \rightarrow p \pi ^0$$ reaction in the resonance region Kim, C. W.; Zachariou, N.; Bashkanov, M. The European Physical Journal A, Vol. 59, Issue 9 https://doi.org/10.1140/epja/s10050-023-01123-3	journal	September 2023
Coherent Bremsstrahlung of Electrons in Crystals Timm, U. Fortschritte der Physik, Vol. 17, Issue 12 https://doi.org/10.1002/prop.19690171202	journal	January 1969
Measurement of Compton Scattering at MAMI for the Extraction of the Electric and Magnetic Polarizabilities of the Proton Mornacchi, E.; Martel, P. P.; Abt, S. Physical Review Letters, Vol. 128, Issue 13 https://doi.org/10.1103/PhysRevLett.128.132503	journal	April 2022
Light Baryon Spectroscopy Thiel, A.; Afzal, F.; Wunderlich, Y. Progress in Particle and Nuclear Physics, Vol. 125 https://doi.org/10.1016/j.ppnp.2022.103949	journal	July 2022
First Measurement of the Helicity Asymmetry for γ p → p π 0 in the Resonance Region Gottschall, M.; Anisovich, A. V.; Bantes, B. Physical Review Letters, Vol. 112, Issue 1 https://doi.org/10.1103/PhysRevLett.112.012003	journal	January 2014
Linearly polarized photons at MAMI (Mainz) Lohmann, D.; Peise, J.; Ahrens, J. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 343, Issue 2-3 https://doi.org/10.1016/0168-9002(94)90230-5	journal	April 1994
Photoproduction of π 0 mesons off protons and neutrons in the second and third nucleon resonance regions Dieterle, M.; Werthmüller, D.; Abt, S. Physical Review C, Vol. 97, Issue 6 https://doi.org/10.1103/PhysRevC.97.065205	journal	June 2018
A Møller polarimeter for CW and pulsed intermediate energy electron beams Wagner, B.; Andresen, H. G.; Steffens, K. H. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 294, Issue 3 https://doi.org/10.1016/0168-9002(90)90296-I	journal	September 1990
Theory of Bremsstrahlung and Pair Production. I. Differential Cross Section Bethe, H. A.; Maximon, L. C. Physical Review, Vol. 93, Issue 4 https://doi.org/10.1103/PhysRev.93.768	journal	February 1954
Extended SAID partial-wave analysis of pion photoproduction Briscoe, William J.; Schmidt, Axel; Strakovsky, Igor Physical Review C, Vol. 108, Issue 6 https://doi.org/10.1103/PhysRevC.108.065205	journal	December 2023
Cross section for γ n → π 0 n measured at the Mainz A2 experiment Briscoe, W. J.; Hadžimehmedović, M.; Kudryavtsev, A. E. Physical Review C, Vol. 100, Issue 6 https://doi.org/10.1103/PhysRevC.100.065205	journal	December 2019
First measurement of the polarization observable E in the p → ( γ → , π + ) n reaction up to 2.25 GeV Strauch, S.; Briscoe, W. J.; Döring, M. Physics Letters B, Vol. 750 https://doi.org/10.1016/j.physletb.2015.08.053	journal	November 2015
Measurement of the helicity dependence for the γ p → n π + channel in the second resonance region Ahrens, J.; Altieri, S.; Annand, J. R. M. Physical Review C, Vol. 74, Issue 4 https://doi.org/10.1103/PhysRevC.74.045204	journal	October 2006
Hybrid baryons in QCD Dudek, Jozef J.; Edwards, Robert G. Physical Review D, Vol. 85, Issue 5 https://doi.org/10.1103/PhysRevD.85.054016	journal	March 2012
Moravcsik's theorem on complete sets of polarization observables reexamined Wunderlich, Y.; Kroenert, P.; Afzal, F. Physical Review C, Vol. 102, Issue 3 https://doi.org/10.1103/PhysRevC.102.034605	journal	September 2020
Measurement of the helicity asymmetry E for the reaction $$ \gamma p\rightarrow \pi ^0 p$$ Gottschall, M.; Afzal, F.; Anisovich, A. V. The European Physical Journal A, Vol. 57, Issue 1 https://doi.org/10.1140/epja/s10050-020-00334-2	journal	January 2021
Photon and Electron Polarization in High-Energy Bremsstrahlung and Pair Production with Screening Olsen, Haakon; Maximon, L. C. Physical Review, Vol. 114, Issue 3 https://doi.org/10.1103/PhysRev.114.887	journal	May 1959
High-Energy Interference Effect of Bremsstrahlung and Pair Production in Crystals Überall, H. Physical Review, Vol. 103, Issue 4 https://doi.org/10.1103/PhysRev.103.1055	journal	August 1956
A Mott polarimeter operating at MeV electron beam energies Tioukine, V.; Aulenbacher, K.; Riehn, E. Review of Scientific Instruments, Vol. 82, Issue 3 https://doi.org/10.1063/1.3556593	journal	March 2011
Double-polarization observable G in neutral-pion photoproduction off the proton Thiel, A.; Eberhardt, H.; Lang, M. The European Physical Journal A, Vol. 53, Issue 1 https://doi.org/10.1140/epja/i2017-12194-8	journal	January 2017
Determining pseudoscalar meson photoproduction amplitudes from complete experiments Sandorfi, A. M.; Hoblit, S.; Kamano, H. Journal of Physics G: Nuclear and Particle Physics, Vol. 38, Issue 5 https://doi.org/10.1088/0954-3899/38/5/053001	journal	April 2011
Photoproduction of neutral pions at backward angles in the resonance region and the ?-cusp Althoff, K. H.; Gies, M.; Kaul, O. Zeitschrift f�r Physik C Particles and Fields, Vol. 1, Issue 4 https://doi.org/10.1007/BF01546970	journal	December 1979
High-Energy Bremsstrahlung and Electron Pair Production in Thin Crystals Palazzi, Giordano Diambrini Reviews of Modern Physics, Vol. 40, Issue 3 https://doi.org/10.1103/RevModPhys.40.611	journal	July 1968
Double polarisation observable G for single pion photoproduction from the proton Zachariou, N.; Watts, D. P.; McAndrew, J. Physics Letters B, Vol. 817 https://doi.org/10.1016/j.physletb.2021.136304	journal	June 2021
Extracting the spin polarizabilities of the proton by measurement of Compton double-polarization observables Paudyal, D.; Martel, P. P.; Huber, G. M. Physical Review C, Vol. 102, Issue 3 https://doi.org/10.1103/PhysRevC.102.035205	journal	September 2020
Upgrade of the Glasgow photon tagging spectrometer for Mainz MAMI-C McGeorge, J. C.; Kellie, J. D.; Annand, J. R. M. The European Physical Journal A, Vol. 37, Issue 1 https://doi.org/10.1140/epja/i2007-10606-0	journal	June 2008
The light-baryon spectrum in a relativistic quark model with instanton-induced quark forces: The non-strange-baryon spectrum and ground states Löring, U.; Metsch, B. Ch.; Petry, H. R. The European Physical Journal A, Vol. 10, Issue 4 https://doi.org/10.1007/s100500170105	journal	June 2001
Measurement of K − p → η Λ near threshold Starostin, A.; Nefkens, B. M. K.; Berger, E. Physical Review C, Vol. 64, Issue 5 https://doi.org/10.1103/PhysRevC.64.055205	journal	October 2001