slide1
Download
Skip this Video
Download Presentation
outline Motivation Experimental Setup A nalysis

Loading in 2 Seconds...

play fullscreen
1 / 7

outline Motivation Experimental Setup A nalysis - PowerPoint PPT Presentation


  • 76 Views
  • Uploaded on

Indications for a structure near the 2 p threshold in the g p p gg reaction. David Trnka II. Physikalisches Institut, University Gießen for TAPS- and CB /ELSA -Collaboration. outline Motivation Experimental Setup A nalysis. Preliminary result from the WASA collaboration.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' outline Motivation Experimental Setup A nalysis' - corine


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
slide1

Indications for a structure near the 2p threshold in the gp pgg reaction

David Trnka

II. Physikalisches Institut, University Gießen

for TAPS- and CB/ELSA-Collaboration

  • outline
  • Motivation
  • Experimental Setup
  • Analysis
slide2

Preliminary result from the WASA collaboration

  • • recently peaklike structure in
  • pp  ppgg near 2p threshold
  • reported i.e. @ DPG/Koeln
  • • angular distrubution consistant
  • with s-wave production
  • • BG: • pp  pppp (15%)
  • • double bremsstrahlung (rest)
  • • artifact peak due to
  • merged clusters (1 count)
  • (2 g‘s from 1 p decaying
  • in a similar way)
  • • pp  ppp+p- (0%)
  • Possible Interpretation:
  •  peak structure due to 2
  • photon radiation in the
  • mesonic s channel:
  • pp  pps  ppgg

Also: CB @ LEAR reanalysing data

slide3

Experimental Setup

accelerator facility [email protected]

side view of experimental area

tagging system:

taggingrange: 22 to 93 % of incident electron beam energy

slide4

4 p detector system

CB/TAPS @ ELSA

Crystal BarrelTAPS

1290 CsI 528 BaF2

side view

front view of TAPS

g

f = 360°

q = 30°to 168°

f = 360°

q = 5°to 30°

slide5

Analysis

• mesons identified via invariant

mass analysis of decay photons

• all beam energies allowed (ca. 500 MeV to 2.5 GeV)

• only tiny fraction of data analysed

• clean up spectra via exclusiv

measurent

require coplanarity

apply missing mass cut

(p treated as missing particle)

slide6

a quick look

comare to WASA

Tp = 1.2 GeV and 1.36 GeV in pp reactions corresponds to

Eg = 0.67 GeV and 0.77 GeV in g p reactions

low beam energies:

• peak structure around 2mp visible

• for solid target structure even below 2mp

slide7

a bit more sophisticated look

• scan through different beam energy bins

• remove/reduce merged cluster candidates

 cut on clustersize ( < 10 crystals)

 cut on opening angle of the photon pair (>20°)

• investigate pp background

bg not yet understood (FWHM = ?)

 slight shift of peak position with beam energy

 more detailed study would be great (CB/TAPS @ MAMI)

ad