CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Coherent and Incoherent  0 Photoproduction on Nuclei Claire Tarbert, University of Edinburgh Experiment spokesperson: Dan Watts

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Outline 1.Status of Incoherent analysis/publication. C-12 status Other targets 2.Status of Coherent analysis/publication. Pb-208: status – cross sections Pb-208: extracting the matter radius MAMI-B data: March/April 2005 E e = 883MeV Pb-208, Ca-40, O-16, C-12

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh IncoherentA(  0 )A* Tagg the final state by coincident detection of nuclear decay gammas. Expect strong anisotropy in decay gamma angular distribution. Incoherent  Nuclear  0 Photoproduction on - 12 C + data -- Geant3

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Incoherent  Nuclear  0 Photoproduction on - 12 C Calculations by Takaki: DWIA +  -hole model Calculations by Tryasuchev: IA + L-S coupling. Published in PRL – last week!

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Incoherent  Nuclear  0 Photoproduction – C-12

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Incoherent  Nuclear  0 Photoproduction – C-12

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Incoherent  Nuclear  0 Photoproduction – E  dependence of C-12 Work in progress…..

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Incoherent  Nuclear  0 Photoproduction – Ca-40 and O-16 O-16Ca-40 Calculation (J  = 3 - final state) :  [ o ] Calculation has been corrected for geometric acceptance of detectors. Need to investigate angular distribution of decay  s more before normalising incoherent cross sections on Ca-40 and O-16. No calculations exist for Ca-40 or O-16.

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Presented finalised total and differential coherent cross sections as a function of pion angle on 208 Pb, 40 Ca, 16 O, 12 C in my thesis. See satisfactory agreement with previous data and theory calculations. At present working on extracting the matter form factor from final normalised cross sections. CoherentA(  0 )A Missing energy analysis to isolate coherent events. Coherent  Nuclear  0 Photoproduction

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Coherent  Nuclear  0 Photoproduction – E  dependence Pb-208 C-12 O-16 Ca-40 + CB data + Glasgow TAPS data Kamalov Calcs: PWIA DWIA Full Calc (DREN)

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Coherent  Nuclear  0 Photoproduction – Pb CB data + Glasgow TAPS data -- DREN (Kamalov)

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Have re- derived cross sections as a function of momentum transfer to the nucleus ….. Coherent  Nuclear  0 Photoproduction – Pb-208

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Pb-208 Without FSI cross section could be descibed by PWIA. FSI has effect of: 1. Changing momentum of outgoing pion as it leaves the nucleus (shift in q). 2. Loss of strength with another channel.

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Pb-208 At least 2 possibilities: 1.Put different matter distributions into the Kamalov model parametrised as a series of Bessel functions. Then do a  2 minimisation against the data. 2.Correct the data for the effects of FSI first => gives a PWIA cross section. Form factor can then be lifted out and r.m.s. matter radius extracted in a number of ways.

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh A simple model to correct for FSI V o = [M 2 +p’ 2 ] 1/2 – [M 2 +p 2 ] 1/2 + [m  2 + p’ 2 ] 1/2 – [m  2 + p 2 ] 1/2 Use complex potential from Kamalov model to approximate V o in simple model. Use shift in the form factor minimum position between the PWIA and DREN calculations to approximate potential height. M mm

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh A simple model to correct for FSI + V calculated using shift in 1 st minimum position + V calculated using shift in 2nd minimum position + V calculated using shift in 3rd minimum position

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh A simple model to correct for FSI Insert beautiful plot here showing that DREN calculations can be corrected back to PWIA.

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Pb-208 E  = ( )MeV Cross section corrected for FSI using simple model. Fitted with a Bessel function

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Pb-208 No skin 0.1fm skin * No correction for FSI * Corrected for FSI Position of first minimum => Non zero neutron skin

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Summary Incoherent reaction Differential cross sections for C-12: PUBLISHED. E  dependence of C-12 cross sections: ANALYSIS BEING FINALISED. In principle can do the same for O-16 and Ca-40: NEED CALCULATIONS. Coherent reaction Have finalised all cross sections as a function of theta. Have finalised Pb-208 cross sections as a function of q. Trying to extract matter radius. Have first draft of paper within 2 months. ……………………………….. IN PROGRESS.

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh End

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh End

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh End

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Still to do Improve resolution if diffraction minima. Fine tune FSI correction. Once have PWIA cross section convert to a F(q) Extract r.m.s. radius

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Working on extracting matter form factor for Pb-208 Postdoc finishes in May 2008 – needs to be done by then! A preliminary look……. Comparison with Krusche TAPS data Comparison with Kamalov Calcs

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Pb-208 Have derived cross sections as a function of momentum transfer to the nucleus …..

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Pb-208 Have derived cross sections as a function of momentum transfer to the nucleus …..

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Coherent  Nuclear  0 Photoproduction – Pb-208 Pb + CB data + Glasgow TAPS data -- DREN

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Pb-208 Have derived cross sections as a function of momentum transfer to the nucleus …..

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Incoherent  Nuclear  0 Photoproduction – C-12

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Incoherent  Nuclear  0 Photoproduction – C-12

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Pb-208

CB Collaboration Meeting, Dubrovnik, 7 April 2008 Claire Tarbert, Univeristy of Edinburgh Extracting the Matter Distribution – Pb fm increase in rms => 0.01fm -1 shift in 1 st minimum position