Institut für Kernphysik V.Hejny1CSB Workshop Trento / June 13-17, 2005 Understanding dd  4 He  0 Experimental Studies at COSY V. Hejny Institut für Kernphysik Forschungszentrum Jülich 1. Near threshold  -production in dd  3 A N  ANKE 2. The future WASA-at-COSY setup 3. p-wave contributions to dd  4 He  0 WASA-at-COSY

Institut für Kernphysik V.Hejny2CSB Workshop Trento / June 13-17, 2005 Charge Symmetry Breaking in dd  4 He 0 Theoretical analysis within ChPT  first results and status: see talks today...  expectation: CSB hadronic matrix elements  10% precision Further experimental constraints and checks needed  e.m. CSB contributions e.g. from dd   0  or   dd  0  test of ISI in a similar, CS conserving reaction  p-waves in dd   0 to be measured with WASA-at-COSY ISI  Prod. d d 00 χPT 3 P 0 (at thr.) χPT ? dd  (A=3) N  I = 1

Institut für Kernphysik V.Hejny3CSB Workshop Trento / June 13-17, 2005 dd  (A=3)N Isospin conserving, same initial state  no free parameters in calculation all fixed from NN  NN   calculations up to N 3 LO:  tot : 10% uncertainty + systematics from ISI Additional aspects  3 H-p / 3 He-p interaction with I=1 fixed  role of 4-body forces Experimentally  lowest (isospin conserving)  -production channels in dd: dd  3 H p  0, 3 He n  0, 3 He p  -, 3 H n  + no data available !  theor. demand:  /  < % (at least) ISI N + 3 A Prod. d d  3 P 0 (at thr.)

V. Hejny 1, A. Magiera 2, M. Büscher 1, D. Chiladze 1, C. Hanhart 1, A. Kacharava 3, A. Khoukaz 4, T. Mersmann 4, M. Śmiechowicz 2, H. Ströher 1, A. Wrońska 1,2 and the ANKE Collaboration 1 Institut für Kernphysik, Forschungszentrum Jülich, Germany 2 Institute of Physics, Jagiellonian University, Cracow, Poland 3 Physikalisches Institut II, Universität Erlangen-Nürnberg, Germany 4 Institut für Kernphysik, Universität Münster, Germany Near Threshold  Production in dd  ( 3 HeN)  and dd  ( 3 HN)  Proposal 139

Institut für Kernphysik V.Hejny5CSB Workshop Trento / June 13-17, 2005 Cooler Synchrotron COSY at FZ Jülich Proton and deuteron beams  p max  3.65 GeV/c (E p = 2.82 GeV, E d = 2.2 GeV)  M Prod  1.1 GeV/c 2 (in pp)  cooling (stochastic, electron)  polarisation Internal installations  thin, windowless gas targets / strip targets  polarized gas targets External installations  extracted, high quality, focussed beams  compact LH 2, LD 2,... targets

Institut für Kernphysik V.Hejny6CSB Workshop Trento / June 13-17, 2005 The ANKE spectrometer ANKE: internal magnetic spectrometer Beam

Institut für Kernphysik V.Hejny7CSB Workshop Trento / June 13-17, 2005 dd  (A=3)N dd  3 H p  0, 3 He n  0, 3 He p  - at threshold  acceptance of ANKE well suited for this kinematics

Institut für Kernphysik V.Hejny8CSB Workshop Trento / June 13-17, 2005 Hit Characteristics in ANKE

Institut für Kernphysik V.Hejny9CSB Workshop Trento / June 13-17, 2005 dd  (A=3)N dd  3 H p  0, 3 He n  0, 3 He p  - at threshold  acceptance of ANKE well suited for this kinematics  March 2005: measurement at COSY/ANKE

Institut für Kernphysik V.Hejny10CSB Workshop Trento / June 13-17, 2005 dd  (A=3)N dd  3 H p  0, 3 He n  0, 3 He p  - at threshold  acceptance of ANKE well suited for this kinematics  March 2005: measurement at COSY/ANKE Goal:  /  < 20-30%  crucial: absolute beam momentum (phase space, i.e.  ~ Q 2 ?) luminosity

Institut für Kernphysik V.Hejny11CSB Workshop Trento / June 13-17, 2005 Normalisation 1.Beam momentum  absolute value from COSY:  p/p ≥  method: continuous ramp from to GeV/c (  Q = 8MeV)  full excitation functions, momentum calibration by crossing all reaction thresholds 2.Luminosity  no data for elastic dd scattering  instead: quasi-elastic pp and pd scattering exploit momentum shift by energy-loss in the target ! - measured by frequency shift in COSY - successfully used in previous ANKE beam times - expected precision < 10 %  ramped beam + fixed beam momentum: t p

Institut für Kernphysik V.Hejny12CSB Workshop Trento / June 13-17, 2005 Status To get  /  < 20-30%: estimated using a non-relativistic model, spectator kinematics: HeN  -events in 10days ( L eff  6 · cm -2 s -1,  nb) Data: first glance  3 He can be identified  event rates in agreement with estimation  at least statistics is fine... d d p n 3 He 00  tot = f(  tot (pd  3 Hep 0 )) 3 He

Institut für Kernphysik V.Hejny13CSB Workshop Trento / June 13-17, 2005 dd  (A=3)N dd  3 H p  0, 3 He n  0, 3 He p  - at threshold  acceptance of ANKE well suited for this kinematics  March 2005: measurement at COSY/ANKE Goal:  /  < 20-30%  crucial: absolute beam momentum (  ~ Q 2 ) luminosity Status  Online: 3 HeN  events identified, statistics within expected range  Offline: energy, time, momentum calibration close to be finished no (preliminary) results available yet

Institut für Kernphysik V.Hejny14CSB Workshop Trento / June 13-17, 2005 The Future: WASA-at-COSY WASA:  4  detector for charged and neutral particles  operated at CELSIUS storage ring, TSL/Uppsala 1m shutdown of CELSIUS end of June 2005 WASA at COSY

Some Features of WASA Pellet target Pellet target  internal, windowless target  H 2 /D 2 pellets, ø = 30  m  L  cm -2 s -1, beam life time  minutes Beam

Some Features of WASA Multi-layer forward detector (enery loss, hit position) Multi-layer forward detector (enery loss, hit position)   = 3°… 18°, tracker resolution 0.2°  stopping ,p,d,  up to 170, 300, 400, 900 MeV  energy resolution 3% (T stopped ) … 8% (2x T stopped ) Beam E dep vs. E kin

Some Features of WASA Inner tracking (straw tube tracker) Inner tracking (straw tube tracker)  superconducting solenoid (0.18·X 0 ), 1.3 T  momentum res. (  p /p):80°2% ( MeV/c) 35°4%-6% 20°6%-10% Beam

Some Features of WASA CsI(Na) electromagnetic calorimeter: CsI(Na) electromagnetic calorimeter:  16·X 0,  = 20° … 170°, full azimuthal acc.  angular res.:  5°  energy res.: 100 MeV 8% charged part. 3% Beam

Institut für Kernphysik V.Hejny19CSB Workshop Trento / June 13-17, 2005 Timeline Jul.-Oct Dismounting WASA at CELSIUS Nov Transfer to COSY Aug Assembly at COSY finished Sep Start commissioning Jan Begin of experimental program

Institut für Kernphysik V.Hejny20CSB Workshop Trento / June 13-17, 2005 Physics: Primary objective Studying fundamental symmetries to understand hadronic systems:  isospin symmetry / quark mass effects  and  ’ decays dd → 4 He  0  C,P,T (violation) and combinations  and  ’ decays further Talks by M.Wolke: “  and  ’ decays with WASA” V.Kleber:“a 0 -f 0 mixing”

Institut für Kernphysik V.Hejny21CSB Workshop Trento / June 13-17, 2005 The WASA at COSY Collaboration 137 Members24 Institutes, 7 Countries Proposal “WASA-at-COSY” available as arXiv:nucl-ex/ (b/w) or at (color)

Institut für Kernphysik V.Hejny22CSB Workshop Trento / June 13-17, 2005 dd  4 Heπ 0 : Proposed studies Theoretical input  consistent analysis of A fb (np  dπ 0 ) and dd  4 Heπ 0  result: parameter-free prediction of p-wave contributions in dd  4 Heπ 0 Experimental program  on-set of p-waves in dd  4 Heπ 0 (proposed: Q = 60 MeV)  contributions from Δ resonance at higher energies  energy dependance: helps to minimize systematics from dd ISI Extraction of p-waves:  problem:no interference of s and p (symmetric initial state) s-d and p-p interferences have same signature  only polarized deuteron beam allows mixed s-p term  measuring asymmetries / analyzing power / d  /d   disentangle s-, p- and d-waves

Institut für Kernphysik V.Hejny23CSB Workshop Trento / June 13-17, 2005 General concept Coincidence measurement of  and  0 in WASA  π 0  γγ in CsI calorimeter -  = 20° … 170°, full azimuthal acc. - angular resolution  5° - energy resolution ( 100 MeV): 8%   in forward detector -  = 3° … 18°, tracker resolution 0.2° - stopping power: E   900 MeV -  p  /p   2-3% low Q Δ resonance 250 MeV 350 MeV

Institut für Kernphysik V.Hejny24CSB Workshop Trento / June 13-17, 2005  identification: Experience at ANKE dd  4 Heη at ANKE  large proton background (np s )d  p s X, pd and pN quasifree same rigidity as  !  cut on energy loss very efficient  however:  ( 4 Heη)  10 3 ·  ( 4 He   ) !

Institut für Kernphysik V.Hejny25CSB Workshop Trento / June 13-17, 2005  identification with WASA More favorable situation at WASA  pion detection: π 0  γγ  further constraints  additional plastic layers for proton rejection  break-up protons remain at  0º (no transverse magnetic field)  however: no momentum reconstruction ΔE vs E tot θ rec vs θ meas Trigger Hodoscope θ rec vs E tot

Institut für Kernphysik V.Hejny26CSB Workshop Trento / June 13-17, 2005 Beam time estimates Goal: extraction of CSB p-wave contributions  asymmetries, angular distributions  N π, tot ≥ 1000 (e.g.  N/N  10% per bin) Luminosity  Polarized deuteron beam N d = 5· ·10 10 in flat top  WASA pellet targetd eff  5·10 15 cm -2 Beam time 1. p-waves between threshold and Δ region Q  60 MeV (p beam  1.2 GeV/c) σ tot, estimated  75 pb  weeks 2. p-wave contributions from Δ resonance Q  160 MeV (p beam  1.6 GeV/c) σ tot, estimated  120 pb  weeks L  3· ·10 32 cm -2 s -1

Institut für Kernphysik V.Hejny27CSB Workshop Trento / June 13-17, 2005 Some crucial points Moderate resolution for  0 and    no time-of-flight, no magnetic field in forward direction   combined analysis / kinematical constraints Background  lower limit in Q defined by WASA beam pipe  break-up channels  0 X open  break-up (beam-)protons (neutrons, beam halo ?)  additional detector elements necessary Statistics  estimated: IUCF result scaled (s-wave)  sensitivity on p-wave component  what to measure: asymmetry / analyzing power / d  /d  ?

Institut für Kernphysik V.Hejny28CSB Workshop Trento / June 13-17, 2005 Summary Charge Symmetry Breaking - a tool to deepen our understanding of QCD symmetries COSY allows selective experiments according to - isospin (protons, deuterons) - spin (polarized beams) dd  (A=3)N  at ANKE - providing data for dd initial state with similar kinematics - in addition: 3 He-p / 3 H-p at I=1, 3-body forces WASA provides - detection of charged and neutral particles - pellet target for highest luminosities WASA at COSY:a tool for decisive investigations on Charge Symmetry Breaking

Institut für Kernphysik V.Hejny29CSB Workshop Trento / June 13-17, 2005 Thank you!

Institut für Kernphysik V.Hejny31CSB Workshop Trento / June 13-17, 2005 WASA: Overview WASA comprises  Pellet Target resulting luminosities: L = cm -2 s -1  Central Detector el.-mag. calorimeter superconducting solenoid mini drift chamber plastic scintillator barrel  Forward Detector trigger hodoscope range hodoscope drift chamber at Cosy: Cerenkov detector

Identification of reaction channels: tp  0 and 3 Hep  - identified by coincidence with proton 3 Hen  0 unambigiously identified up to threshold  for higher momenta:  ( 3 Hen  0 ) =  ( 3 HeN  ) -  ( 3 Hep  - ) however: extraction of tn  + the same way is difficult 

Institut für Kernphysik V.Hejny34CSB Workshop Trento / June 13-17, 2005 Charge-Symmetry Breaking Charge Symmetry: Charge Symmetry:rotation in isospin space, 180º around I 2 -axis interchange of u  d quarks Approximate symmetry in QCD:  quark-mass differences, m u  m d  different electromagnetic corrections for u and d-quark CSB is an experimental handle on these effects Recent results:  A fb (np  d  0 ) (Opper et al., PRL 91, )  dd   0 at threshold (Stephenson et al., PRL 91, 14302)  cross section would vanish in a charge-symmetric world  direct measurement of CSB-amplitude squared Task: extraction of CSB hadronic matrix elements

Institut für Kernphysik V.Hejny35CSB Workshop Trento / June 13-17, 2005 ChPT Effective Lagragian links various observables: Nucleon mass splitting: m n - m p = ΔM str + ΔM em = 1.26 MeV  ΔM str,ΔM em not known individually  ΔM em  - (0.76  0.30) MeV (negative!)  additional contraints desirable πN scattering length  a(π 0 p) - a(π 0 n) = f(ΔM str )  however: no direct measurement of π 0 N large e.m. corrections in π  N  instead: πN rescattering in pion production f(ΔM str - 1/2 ΔM em ) Exploiting CSB Nπ X Nπ N X

Institut für Kernphysik V.Hejny36CSB Workshop Trento / June 13-17, 2005 Here: dd  4 He  0 Pion production in dd  4 Heπ 0  σ  0 in a charge symmetric world  σ  |M CSB | 2  complementary to np  dπ 0 : different strength of CSB terms dd initial state more demanding  recent result: Stephenson et al. (PRL 91 (142302) 2003)  tot (Q  1.4 MeV)= 12.7  2.2 pb  tot (Q  3.0 MeV)= 15.1  3.1 pb consistent with s-wave Q  1.4 MeV Q  3.0 MeV International Workshop on Charge Symmetry Breaking June 13-17, 2005, ECT, Trento, Italy

Institut für Kernphysik V.Hejny37CSB Workshop Trento / June 13-17, 2005 Production Rates of ’ In comparison: Da  ne/KLOE  ’ by mid 2005 similar statistics in ~ 4 days from WASA at COSY