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A-dependence of deuteron knock out from light nuclei by intermediate energy pions

A-dependence of deuteron knock out from light nuclei by intermediate energy pions B.M.Abramov, Yu.A.Borodin, S.A.Bulychjov, I.A.Dukhovskoy, A.I.Khanov, A.P.Krutenkova, V.V.Kulikov , M.A.Martemianov, M.A.Matsyuk, V.E.Tarasov,

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A-dependence of deuteron knock out from light nuclei by intermediate energy pions

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  1. A-dependence ofdeuteron knock out from light nuclei by intermediate energy pions B.M.Abramov, Yu.A.Borodin, S.A.Bulychjov, I.A.Dukhovskoy, A.I.Khanov, A.P.Krutenkova, V.V.Kulikov, M.A.Martemianov, M.A.Matsyuk, V.E.Tarasov, E.N.Turdakina. ITEP, Moscow A(π--, d π-- )X A= Li-6, Li-7, C-12, O-16 0.7, 0.9 and 1.3 GeV/c

  2. Motivation for deuteron and triton knock out study 1. Reaction mechanism. 2. Nuclear structure: nucleon-nucleon correlations, clustering properties etc. 3. Possible modification of deuteron properties innuclear media. 4. Different projectiles are disirable to have a full picture of nuclear fragment knock out processes. Data exist on proton, electron and photon beams but not on a pion beam. 5. High energy and large momentum transfer are important to minimize distortion 6. Clustering aspects of Li isotopes

  3. Main problems of deuteron knock out experiments with pion beam. 1. An intensity of pion beams is smaller than that of proton. 2. Cross secion for the backward pion deuteron elastic scattering is less by two oders of magnitude than cross section for backward proton deuteron elastic scattering. 3. Non favourable kinematics and large additional pion production in pion beam make it impossible to observe the peak of quasielastic scattering without detection of scattered pion.

  4. p+A->d+X, 660 MeV, L.S.Azhgirei ..(JINR) π+A->d+X, 0.7 GeV/c, B.M.Abramov ..(ITEP)

  5. ITEP 3-meter magnet spectrometer

  6. Trigger ~100 PM FEY-60, 85, 30, 63 d: - ->d- B= (H1·C2·C3)·(antiC5) B·(H5·H2·H3)·(C7+H4) ·(C2·H3)td p: - ->p- B·(H2·H3)·(C7+H4) ; : - ->+B·(H5·H2·H3)·(C2·H3)t Beam: 0.72, 0.88, 1.3 GeV/c; p/p=1.5%; p/p=0.2%; I=(5-1) ·105 /burst. Targets: Li-6((90%), Li-7, C-12, O-16 in H2O, D2O ;10x10 cm Spark Ch. 70 gaps, ~30 space points/track, Ne-He, <5pictures/burst Data: 0.75M pictures->taken->scanned->processed->analysed a lot of on-line/off-line/MC/physics software

  7. Deuteron/triton selection by TOF Mass of the flying particle was calculated using known momentum and TOF

  8. Plane Wave Impulse Approximation Pd PB π d PF π Pπ Li-6 X X= He-4, He*, dd, dpn ….. PF = PB - Pd - Pπ ; MX2= (PB + PT - Pd ) 2 Emiss = TB - Td - Tπ = Md + MHe - Mli + E*He + TF dN = nddσ(πd)NbNLiKε(PF ,Emiss)

  9. πd - elastic scattering on heavy water target MX2= Mπ2 =0.02 GeV2 for free deuteron MX2= (PB + PT - Pd ) 2 D2O PF = PB - Pd - Pπ T Pd Events PB PF <70 MeV/c Pπ PF = 0 for free deuteron 70 MeV/c cut Events H2O σP = 20 MeV/c PF ,GeV/c MX2, GeV2

  10. Emiss resolution as measured on D2O target at 0.7 GeV/c Emean = 1.15 MeV σ = 15.5 MeV GeV For Li-isotopes due to smaller multiple scattering in the target Emiss resolution is 9.5 MeV.

  11. Comparison of the measured differential cross section for backward pion deuteron scattering on free deuteron with data of Kelleret al.

  12. Li-6, 0.7 GeV/c Nd=1.90+-0.15 He-4 (0.60) Emiss = 1.5 MeV Emiss>22 MeV dd (0.65) dpn (0.65) Excitation energy distribution for rest nucleus for deuteron knock out from Li-6

  13. Li-7, 0.7 GeV/c (2 /n.d.f.=18/12) He-5 hypothesys 5Heg.s.(0,55) 5Hee.s.(1.0) Excitation energy distribution for rest nucleus for deuteron knock out from Li-7

  14. C-12, 0.7 GeV/c Emean = 43+/-2 MeV σ = 22+/-2 MeV Nd = 1.73+/-0.15 Emiss GeV Excitation energy distribution for rest nucleus for deuteron knock out from C-12 ∆E 0-35 35-60 60-100 Nd 0.39+/-0.06 0.71+/-0.11 0.63+/-0.14 Nd 0.32+/-0.01 McGregor et al. (γ,pn),150 MeV

  15. O-16, 0.7 GeV/c Emean = 34+/-2 MeV σ = 18+/-2 MeV Nd = 1.40+/-0.16 GeV Emiss Excitation energy distribution for rest nucleus for deuteron knock out from O-16

  16. (p,d) inclusive A0.66 (,d) full kinematics Effective number of quasideuterons as a function of atomic number A.

  17. Straight line approximation for particle absorption in nuclear media b Lb=0.55 Fm Ld=Lb/3 Ls=Lb/4 RA X beam pion d scattered pion

  18. Sutter(BNL) Azhgirey(JINR) (p,d) Neff A0.33 Arefiev(ITEP) π,dπ (p,d) Neff This experiment π,dπ A

  19. ρ(r) (p,d) Pb Number of events (π,dπ) b, Fm (p,d) ρ(r) C-12 (π,dπ) b, Fm

  20. Different A - dependences ~ R2 = A 2/3 ~hR = A 1/3 h h*2R = (L/2)2 L ~ hR ~ L2 = const h

  21. CONCLUSION • For the first time the quasielastic deuteron • knock out hasbeen studied on pion beam • in full kinematics. • Peak of quasielastic deuteron knock out is • clearly seen on all nuclei. It shows that single • step mechanism dominates. • 3. A-dependence of effective numbers of • participating deuterons is practically • constant from Li-6 to O-16 showing large • difference in comparison with measurements • of inclusive deuteron knock out by protons. • 4. Simple calculations indicate that such • a dependence can be connected with larger • absorption for deuteron knock out in full • kinematics measurements.

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