09/10/2005NSTAR2005 - Graal collaboration1 The Graal collaboration results and prospects Presented...
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Transcript of 09/10/2005NSTAR2005 - Graal collaboration1 The Graal collaboration results and prospects Presented...
09/10/2005 NSTAR2005 - Graal collaboration 1
The Graal collaborationresults and prospects
Presented by
Carlo SchaerfUniversità di Roma “Tor Vergata” and INFN - Sezione Roma II
for the Graal collaboration
NSTAR 2005 INTERNATIONAL WORKSHOP
ON THE PHYSICS OF EXCITED BARYONS12 - 15 October 2005, Tallahassee, Florida USA
09/10/2005 NSTAR2005 - Graal collaboration 2
Ladon beams in the world
Graal:
E = 0.6-1.5 GeV / W=1.4-1.9 GeV
Region of the second and third baryon resonances
, K, ’ thresholds
Complementarity of HIGS, LEGS, Graal and LEPS
’ threshold
threshold
K threshold
LEGS/BNL LEPS/SPRING8
(b)
threshold
GRAAL/ESRF
HIGS/FEL/DukeE (GeV)
09/10/2005 NSTAR2005 - Graal collaboration 3
Ladon beams in the world TABLE I Ladon Beams in the World
Project name Ladon° Taladon+ ROKK∆-1M LEGS* LEGS-2 Graal** LEPS† HIGS⊕
ocation Fracati (NF-INFN) Novoibirk Brookaven (BN) Grenoble Haria Dura
Storae rin Adone Adone VE PP-4M NSS NSS ESRF SPrin-8 TUNL -FELL
Enery definin etod colliation internal tain
tain external tain
external tain
internal tain
internal tain
colliation
Electron enery GeV 1.5 1.5 1.4 - 5.3 2.5 2.8 6.04 8 1.0
Poton enery eV 2.45 2.45 1.17-3.51 3.53 4.71 3.53 3.53 8.2
Gaa-ray enery MeV 5-80 35-80 100-1200 180-320 285-470 550-1470 1500-2400 5-225
variable iultaneou variable
Enery reolution % 1.4-10 5 -- 1.6 1.1 1.1 1.25 1
(FWHM) MeV 0.07-8 4-2 -- 5 5 16 30
Electron current A 0.1 0.1 0.1 0.2 0.2 0.2 0.1 100
Gaa intenity -1 105 5 105 2 106 4 106 2 106 2 106 2 106 106-108
Year of operation 1978 1989 1993 1987 1999 1996 1999
° Laer ADONe +TA ed LADON ∆ROKK i a ruian abbreviation for Backcattered Co pton Ga a * Laer Electron Ga a Source ** GRenoble Anneau Accelerateur Laer † aer-Electron Poton at SPrin-8 ⊕ Hi Intenity Ga a-ray Source.
, "r i v i er e d e Gr ece, au Pél op on n èse d ans l'A rc ad i e. . . . l es M yth ol ogis tes f ir en t l e Lad on p er e d e l a n ymph e Daphn é & d e l a n ymph e Syr in x . I l étoit cou vert d e magni f iqu es r oseau x , d on t Pan se ser vi t p our sa f lû te à sep t tu yau x . ” (M . Did er ot an d M . D'A l em ber t , Enc yc l op édi ,e a Par i s M DC CLV I )I
09/10/2005 NSTAR2005 - Graal collaboration 4
Ladon beam polarization
The first verification of the polarization of Ladon beams was performed at Frascati with the elastic scattering of the Ladon gamma-ray beam on the 15.1 MeV level of 12C using the small NaI crystal ball (7 x 16f ) of the University of Rome "La Sapienza". The experimental points reproduce very well the (1+cos2f) law expected for a fully polarized beam on a perfect polarization analyser.
09/10/2005 NSTAR2005 - Graal collaboration 5
Graal beam energyMaximum gamma-ray energies for E=6.04 GeV electrons
k1 z kmax Wmax xtag
E=6.04 GeV
nm
eV
4 k1
E
m2
GeV
GeV
mm
Nd YAG 1064.0 1.17 0.1083 0.590 1.410 17.32 Ar Ion Green 514.5 2.41 0.2230 1.101 1.717 35.67 Ar Ion G-B 488.0 2.54 0.2350 1.149 1.743 37.59 Ar Ion UV 351.1 3.53 0.3266 1.487 1.916 52.26 Ar Ion UV 320.0 3.87 0.3581 1.593 1.967 57.32 Ar Ion UV 300.0 4.13 0.3819 1.669 2.003 61.09 Nd Yag x 4 266.0 4.66 0.4312 1.820 2.073 69.00 Ar Ion G x 2 257.2 4.82 0.4460 1.863 2.092 71.36
Ar Ion G-B x 2 244.0 5.08 0.4700 1.931 2.122 75.19
09/10/2005 NSTAR2005 - Graal collaboration 6
Graal beam energy and thresholds
channel threshold (GeV) kmax (GeV) kmax- kth + p → + p 0.707 1.101 0.394
+ p→ ++ 0.911 1.149 0.238
+ p→ ++ 0 1.046 1.487 0.441
+ p→ + p 1.086 1.487 0.401 + p→ + p 1.108 1.487 0.379 + p→ + ' p 1.447 1.669 0.222 + p→ f 0+ p 1.492 1.669 0.177 + p→ + p 1.573 1.669 0.096
09/10/2005 NSTAR2005 - Graal collaboration 7
Graal beam polarization
Absolute value
09/10/2005 NSTAR2005 - Graal collaboration 8
Graal beam polarizationTheoretical linear polarization of
the -ray beam for two laser
lines: l =514 nm (green line)
and l =351 nm (UV line). The threshold energy of the tagging system is also shown
Green line UV line
09/10/2005 NSTAR2005 - Graal collaboration 9
The Graal Apparatus
Cross section of the BGO ball15 x 32=480
12
6
0
4
5
3
247
9
8
1413
12
11
10
3130
20
26
19
17
25
1816 15
22
23
21
2829
27
09/10/2005 NSTAR2005 - Graal collaboration 10
The Graal Experimental Program
We have enough data Results have been publishedand more are coming
Preliminary results are available but we want more data
We need more data and more efforts on the analysis
€
r + p → π 0 + pr γ + n → π 0 + n
r γ + p →η + p
r γ + n →η + n
r γ + p → π + + n
r γ + p → K + + Λ
r γ + p → 2π 0 + p
r γ + p → K + + Σ0
r γ + n → K 0 + Λr γ + n → K + + Σ−
r γ + p → K 0 + Σ+
r γ + p → γ + p
r γ + n → γ + n
09/10/2005 NSTAR2005 - Graal collaboration 11
Time Of Flight resolutionTypical experimental Time Of Flight spectrum for the thin monitor versus the tagging counters. The distance between two
adjacent peaks is 2.8 ns corresponding to the distance between successive electron bunches. The timing
resolution is ≈ 0.3 ns (FWHM). The level of accidental coincidences in the main peak is less than 0.15%.
2.8 ns
≈ 0,3 ns
09/10/2005 NSTAR2005 - Graal collaboration 12
Two photon spectrum at the p0 mass
2 invariant mass spectrum around the p0 mass. Data (closed circles), before and after all kinematical cuts are applied, are compared with the simulation (solid line). The experimental width of the peak is ≈ 33 MeV (FWHM).
x 2≈ 33 MeV
FWHM
09/10/2005 NSTAR2005 - Graal collaboration 13
The azimuthal distribution in
Yields as a function of
for one value of and E:
a) Vertical polarization;b) Horizontal polarization;c) Sum of a and b;d) The ratio (a-b)/(a+b)
The solid line in d presents a fit of the type:
€
nV −nH
nV +nH= Pγ Σ cos(2ϕ )
€
r + p → π 0 + p
09/10/2005 NSTAR2005 - Graal collaboration 14
Green-UV data comparison
S
E=830 MeV E=865 MeV E=900 MeV
E=930 MeV E=965 MeV E=995 MeV
E=1025 MeV E=1055 MeV E=1090 MeV
€
ϑp 0CM
Comparison of the data obtained with the Green laser line and the UV. The different laser lines produce -ray spectra with different intensities
and polarizations.
€
r + p → π 0 + p
09/10/2005 NSTAR2005 - Graal collaboration 15
+ p p+ p0 S Asymmetry
• Graal o Erevan
SAID-FA04 Erevan S + Bonn dMAID2005 Bonn d + Graal SBonn2005 pN + N + K + KS + Graal S
09/10/2005 NSTAR2005 - Graal collaboration 16
+ p p+ p0 Differential cross section L.E.
• Graal * Bonn
SAID-FA04MAID2005Bonn2005
09/10/2005 NSTAR2005 - Graal collaboration 17
+ p p+ p0 Differential cross section H.E.
SAID-FA04MAID2005Bonn2005
09/10/2005 NSTAR2005 - Graal collaboration 18
Preliminary
+ p +(n) -> p°+ p +(n) Quasi-free proton (uv data)
Free proton
+p-> p°+p Said WI00 (free proton)GRAAL data are not included
Said FA01 (free proton)GRAAL data up to 1100 MeV are included
+ p +(n) -> p°+ p +(n) Quasi-free proton (green)
p° S for free and quasi-free proton
09/10/2005 NSTAR2005 - Graal collaboration 19
Error bars: only statistical errors
+ n +(p)->p0+n +(p)
Said (free neutron)Maid (free neutron)
Green Line
UV Line
Systematic errors <1.5%
po S for quasi free neutron 1/2 L. E.
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 20
Error bars: only statistical errors
+ n +(p)->p0+n +(p)
Said (free neutron)Maid (free neutron)
Green Line
UV Line
Systematic errors <1.5%
po S for quasi free neutron 1/2 H. E.
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 21
Quasi-free proton
Quasi-Free neutron
Preliminary
Comparison of beam asymmetry S for po photo-production on quasi-free proton and quasi-free
neutronlow energy bins
09/10/2005 NSTAR2005 - Graal collaboration 22
Quasi-free proton
Quasi-Free neutron
Comparison of beam asymmetry S for po photo-production on quasi-free proton and quasi-free
neutronhigh energy bins
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 23
59 MeVFWHM
Mass (GeV) Mass (GeV)
Mass after Cuts with simulation
after cuts
before kinematical cuts
from proton from neutron
invariant mass
€
+d → p + n +η
09/10/2005 NSTAR2005 - Graal collaboration 24
€
N1 / K1
N1 / K1 + N2 / K2
=1
2• 1+ P Σ cos 2φ( )[ ]
f
+p+(n)->+p+(n)
+n+(p)->+n+(p)
Azimuthal Distribution:
09/10/2005 NSTAR2005 - Graal collaboration 25
S for the +p+(n)->+p+(n)
Error bars: only statistical errors
Said-BO12 Maid
S for quasi free proton: Gr vs UV Green Line
UV Line
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 26
cm (deg)
Preliminary
Said-BO12 (free proton)
Maid (free proton)
+ p + (n) -> + p + (n) Quasi-free proton
Free proton + p -> + p
S for free and quasi-
free proton
09/10/2005 NSTAR2005 - Graal collaboration 27
Comparison of S of photoproduction on
+p+(n)->+p+(n) Quasi-free proton
Quasi-Free neutron+n+(p)->+n+(p)
quasi-free proton and quasi-free neutron
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 28
Summary of resultsFirst results have been obtained on the analysis of the and po
photoproduction on the quasi-free proton and neutron on a deuteron target:differences in the behaviour start to appear at E=1 GeV.
Results show: photoproduction: qfp and free proton similar behavior
qfn and qfp similar behavior up to 1.2 GeV
po photoproduction: qfp and free proton similar behavior qfn and qfp different
behaviour at higher energy bins: NO change of sign for the neutron
09/10/2005 NSTAR2005 - Graal collaboration 29
Asymmetry S in +p K+
€
p + π −
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 30
Asymmetry S in +p K++ S0
€
↓+
↓p + π−
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 31
Polarization in +p K+
€
↓p + π−
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 32
S Polarization in +p K+ S0
€
+p + π −
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 33
Invariant mass:
n vs p. Neutron in Forward Detector
Preliminary
09/10/2005 NSTAR2005 - Graal collaboration 34
Invariant -n mass
(FD vs BGO)
Dashed Line Neutron in the
Forward Detectorn
Lab < 25°
Solid Line Neutron in the BGO n
Lab > 25° Preliminary
nLab < 25°
nLab > 25°
09/10/2005 NSTAR2005 - Graal collaboration 35
Vacuum-Assisted Photoionization
09/10/2005 NSTAR2005 - Graal collaboration 36
Green laser line
UV laser lines
A typical accuracy of 0.03 microstrip (= 9 ) is obtained for the position of a given line, corresponding to 0.2 MeV.
€
Eγ max =4γ 2Elaser
1+4γ Elaser
me
≈ 4γ 2Elaser
€
DEγ
Eγ
≈ 2 ⋅10−4;Δγ
γ≈
1
2
ΔEγ
Eγ
≈ 10−4
€
=Ee
me
=6030
0.511=11 800; γ 2 ≈ 1.4 ⋅108
€
Db =1
γ 2
⎛
⎝ ⎜
⎞
⎠ ⎟Δγ
γ≈ 10−8 ⋅10−4 ≈ 10−12
€
d Eγ
Eγ
≈ 2dγ
γ; β dβ =
1
γ 2
⎛
⎝ ⎜
⎞
⎠ ⎟dγ
γ
Light Speed Anisotropy 1/5
Microstrip channels: 1 channel = 0.3 mm
09/10/2005 NSTAR2005 - Graal collaboration 37
Light Speed Anisotropy 2/5
Our “absolute” velocities
Rotation of the earth around its axis ≈ 0.32 km/s (Grenoble)
Revolution of the earth around the sun ≈ 30 km/s
Velocity of the Solar System in the Galaxy ≈ 215 km/s
Velocity of the Local Group of Galaxies ≈ 600 km/s
Motion relative to the Last Scattering Surface ≈ 370 km/s
(Velocity of light: c = 299 792 km/s)
09/10/2005 NSTAR2005 - Graal collaboration 38
Light Speed Anisotropy 3/50.1 div = 30 m
09/10/2005 NSTAR2005 - Graal collaboration 39
Light Speed Anisotropy 4/50.001 div = 0,3 m
09/10/2005 NSTAR2005 - Graal collaboration 40
The Graal beam line has been used also for some measurements of more fundamental physics. The most interesting result is a “Probe of the Light Speed Anisotropy With Respect to the Cosmic Microwave Background Radiation Dipole” . This measurement has been made possible by the high stability of the ESRF machine and the very good reproducibility of the Graal gamma-ray spectra. Many years of data have been used to plot the maximum gamma-ray energy as a function of the orientation of the Graal-ESRF interaction region with respect to the absolute direction of the Cosmic Microwave Background Radiation Dipole. Our result sets an upper limit on the anisotropy of the velocity of light of:
This limit is two-three orders of magnitude better than the one obtained from measurements involving space probes.
Mod. Phys. Lett. A 20, N. 1, 19-28 (2005)
€
Dcc
≤ 3 ⋅10−12
Light Speed Anisotropy 5/5