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A. Budzanowski,
A. Chatterjee,
P. Hawranek,
R. Jahn,
V. Jha,
K. Kilian,
S. Kliczewski,
Da. Kirillov,
Di. Kirillov,
D. Kolev, [......],
N. Piskunov,
D. Protić,
J. Ritman,
P. von Rossen,
B. J. Roy,
I. Sitnik,
R. Siudak,
R. Tsenov,
J. Urban, G. Vankova
[show abstract]
[hide abstract]
ABSTRACT: The cross section for the reaction $p+^6\text{Li}\to\eta+^7\text{Be}$ was
measured at an excess energy of 11.28 MeV above threshold by detecting the
recoiling $^7$Be nuclei. A dedicated set of focal plane detectors was built for
the magnetic spectrograph Big Karl and was used for identification and four
momentum measurement of the $^7$Be. A differential cross section of
$\frac{d\sigma}{d\Omega}=(0.69\pm{0.20}\text{(stat.)}\pm
0.20\text{(syst.)})\text{nb/sr}$ for the ground state plus the 1/2$^-$ was
measured. The result is compared to model calculations.
10/2010;
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A. Budzanowski,
A. Chatterjee,
P. Hawranek,
R Jahn,
V. Jha,
K. Kilian,
Da. Kirillov,
Di. Kirillov,
S. Kliczewski,
D Kolev, [......],
J. Ritman,
P. von Rossen,
B. J. Roy,
I. Sitnik,
R. Siudak,
H. J. Stein,
R. Tsenov,
J. Urban, G. Vankova,
C. Wilkin
[show abstract]
[hide abstract]
ABSTRACT: Inclusive measurements of pion production in proton--proton collisions in the forward direction were undertaken at 400 and 600 MeV at COSY using the Big Karl spectrograph. The high resolution in the $\pi^+$ momentum ensured that there was an unambiguous separation of the $pp\to {\pi}^+d/\pi^+pn$ channels. Using these and earlier data, the ratio of the production cross sections could be followed through the $\Delta$ region and compared with the predictions of final state interaction theory. Deviations are strongly influenced by long-range terms in the production operator and the tensor force in the final $pn$ system. These have been investigated in a realistic $pp\to\pi^+d/\pi^+pn$ calculation that includes $S \rightleftharpoons D$ channel coupling between the final nucleons. A semi-quantitative understanding of the observed effects is achieved. Comment: 10 pages, 3 figures
04/2009;
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V Jha,
A Budzanowski,
A Chatterjee,
P Hawranek,
R Jahn,
B K Jain,
S Kailas,
K Kilian,
S Kliczewski,
Da Kirillov, [......],
D Proti,
J Ritman,
P Von Rossen,
B J Roy,
P Shukla,
I Sitnik,
R Siudak,
R Tsenov,
J Urban, G Vankova
[show abstract]
[hide abstract]
ABSTRACT: We have performed an experiment to search for the bound state of η meson in nuclei. We have measured the reaction p + 27 Al → 3 He + p + π − + X at recoil-free kinematics. An η meson possibly produced in this reaction would be thus almost at rest in the laboratory system and could therefore be bound with high probability, if bound nuclear η states exist. The decay of such a state through the N * (1535) resonance would lead to a proton-π − pair emitted in opposite directions. For these conditions we find some indication of such a bound state. An upper limit of ≈ 0.5 nb for the formation cross section is found.
International Journal of Modern Physics E. 01/2009; 18(6):1378-1382.
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A Budzanowski,
A Chatterjee,
P Hawranek,
R Jahn,
B K Jain,
V Jha,
S Kailas,
K Kilian,
S Kliczewski,
Da Kirillov, [......],
D Proti,
J Ritman,
P Von Rossen,
B J Roy,
P Shukla,
I Sitnik,
R Siudak,
R Tsenov,
J Urban, G Vankova
[show abstract]
[hide abstract]
ABSTRACT: We have studied the reaction p + 27 Al → 3 He + p + π − + X at recoil-free kinematics. An η meson possibly produced in this reaction would be thus almost at rest in the laboratory system and could therefore be bound with high probability, if nuclear η states exist. The decay of such a state through the N * (1535) resonance would lead to a proton-π − pair emitted in opposite directions. For these conditions we find some indication of such a bound state. An upper limit of ≈0.5 nb is found.
RAPID COMMUNICATIONS PHYSICAL REVIEW C. 01/2009; 79.
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The GEM Collaboration,
A. Budzanowski,
A. Chatterjee,
R. Gebel,
P. Hawranek,
R Jahn,
V. Jha,
K. Kilian,
S. Kliczewski,
Da. Kirillov, [......],
D. Protić,
J. Ritman,
P. von Rossen,
B. J. Roy,
U. Sitnik,
R. Siudak,
R. Tsenov,
J. Urban, G. Vankova,
C. Wilkin
[show abstract]
[hide abstract]
ABSTRACT: The angular distributions of the unpolarised differential cross section and tensor analysing power $A_{xx}$ of the $\vec{d}d\to\alpha \eta$ reaction have been measured at an excess energy of 16.6 MeV. The ambiguities in the partial-wave description of these data are made explicit by using the invariant amplitude decomposition. This allows the magnitude of the s-wave amplitude to be extracted and compared with results published at lower energies. In this way, firmer bounds could be obtained on the scattering length of the $\eta \alpha$ system. The results do not, however, unambiguously prove the existence of a quasi-bound $\eta \alpha$ state. Comment: 20 pages, 11 figures
11/2008;
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Gem Collaboration,
P. K. Biswas,
A. Budzanowski,
A. Chatterjee,
R. Jahn,
S. Guha,
P. Hawranek,
B. K. Jain,
S. B. Jawale,
V. Jha, [......],
J. Ritman,
P. von Rossen,
B. J. Roy,
P. Shukla,
I. Sitnik,
R. Siudak,
R. Tsenov,
M. Ulicny,
J. Urban, G. Vankova
[show abstract]
[hide abstract]
ABSTRACT: A large acceptance scintillator detector with wavelength shifting
optical fibre readout has been designed and built to detect the decay
particles of η-nucleus bound system (the so-called η-mesic
nuclei), namely, protons and pions. The detector, named as ENSTAR
detector, consists of 122 pieces of plastic scintillator of various
shapes and sizes, which are arranged in a cylindrical geometry to
provide particle identification, energy loss and coarse position
information for these particles. A solid angle coverage of ˜95% of
total 4π is obtained in the present design of the detector. Monte
Carlo phase space calculations performed to simulate the formation and
decay of η-mesic nuclei suggest that its decay particles, the
protons and pions are emitted with an opening angle of
150±20, and with energies in the range of 25 300 and
225 450 MeV, respectively. The detailed GEANT simulations show that
˜80 % of the decay particles (protons and pions) can be detected
within ENSTAR. Several test measurements using alpha source, cosmic-ray
muons, etc. have been carried out to study the response of ENSTAR
scintillator pieces. The in-beam tests of fully assembled detector with
proton beam of momentum 870MeV/c from the Cooler synchrotron COSY have
been performed. The test results show that the scintillator fibre design
chosen for the detector has performed satisfactorily well. The present
article describes the detector design, simulation studies, construction
details and test results.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 06/2007; 578:198-206. · 1.21 Impact Factor
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K. Kilian,
S. Kliczewski,
Da. Kirillov,
Di. Kirillov,
D Kolev,
M. Kravcikova,
T. Kutsarova,
M. Lesiak,
J. Lieb,
H. Machner, [......],
J. Ritman,
P. von Rossen,
B. J. Roy,
P. Shukla,
I. Sitnik,
R. Siudak,
R. Tsenov,
M. Ulicny,
J. Urban, G. Vankova
[show abstract]
[hide abstract]
ABSTRACT: A large acceptance scintillator detector with wavelength shifting optical fibre readout has been designed and built to detect the decay particles of $\eta$-nucleus bound system (the so-called $\eta$-mesic nuclei), namely, protons and pions. The detector, named as ENSTAR detector, consists of 122 pieces of plastic scintillator of various shapes and sizes, which are arranged in a cylindrical geometry to provide particle identification, energy loss and coarse position information for these particles. A solid angle coverage of $\sim$95% of total 4$\pi$ is obtained in the present design of the detector. Monte Carlo phase space calculations performed to simulate the formation and decay of $\eta$-mesic nuclei suggest that its decay particles, the protons and pions are emitted with an opening angle of 150$^\circ \pm 20^\circ$, and with energies in the range of 25 to 300 MeV and 225 to 450 MeV respectively. The detailed GEANT simulations show that $\sim$ 80 % of the decay particles (protons and pions) can be detected within ENSTAR. Several test measurements using alpha source, cosmic-ray muons etc. have been carried out to study the response of ENSTAR scintillator pieces. The in-beam tests of fully assembled detector with proton beam of momentum 870 MeV/c from the Cooler synchrotron COSY have been performed. The test results show that the scintillator fiber design chosen for the detector has performed satisfactorily well. The present article describes the detector design, simulation studies, construction details and test results.
06/2007;
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V Jha,
A Budzanowski,
A Chatterjee,
J Ernst,
P Hawranek,
K Kilian,
S Kliczewski,
Da Kirillov,
Di Kirillov,
D Kolev, [......],
D Proti,
P Von Rossen,
B J Roy,
P Shukla,
I Sitnik,
R Siudak,
R Tsenov,
M Ulicny,
J Urban, G Vankova
[show abstract]
[hide abstract]
ABSTRACT: An experiment to search for the bound state of η meson in nuclei has been performed at COSY, Juelich using the ENSTAR detector and Big Karl magnetic spectrometer. Reaction (p, 3 He) on 27 Al target has been used to search for the η-mesic nucleus 25 Mgη in the missing mass distribution from the measured 3 He particles. A preliminary figure of 1.5 nb for the upper limit of the formation cross section of η-nucleus bound state has been determined.
International Journal of Modern Physics A. 01/2007; 22(3):596-599.
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M Abdel-Bary,
A Budzanowski,
A Chatterjee,
J Ernst,
R Gebel,
P Hawranek,
R Jahn,
V Jha,
K Kilian,
S Kliczewski, [......],
D Proti,
P Von Rossen,
B J Roy,
I Sitnik,
R Siudak,
R Tsenov,
M Ulicny,
J Urban, G Vankova,
C Wilkin
[show abstract]
[hide abstract]
ABSTRACT: Measurement of the d + d → 4 He + η reaction using vector and tensor polarised beam has been performed at COSY using Big Karl magnetic spectrograph. The beam polarisation necessary for obtaining the vector and tensor analysing power for this reaction was measured. The method and the results of the tensor polarisation measurement of the deuteron beam are presented.
01/2006;
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The GEM Collaboration: M. Lesiak,
M. Abdel-Bary,
A. Budzanowski,
A. Chatterjee,
J Ernst,
R. Gebel,
P. Hawranek,
R Jahn,
V. Jha,
K. Kilian, [......],
D. Protic,
P. von Rossen,
B. J. Roy,
I. Sitnik,
R. Siudak,
R. Tsenov,
M. Ulicny,
J. Urban, G. Vankova,
C. Wilkin
[show abstract]
[hide abstract]
ABSTRACT: Measurement of the d + d -> 4He + eta reaction using vector and tensor polarised beam has been performed at COSY using Big Karl magnetic spectrograph. The beam polarisation necessary for obtaining the vector and tensor analysing power for this reaction was measured. The method and the results of the tensor polarisation measurement of the deuteron beam are presented.
01/2006;
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The GEM collaboration: M. Abdel-Bary,
A. Budzanowski,
A. Chatterjee,
J Ernst,
P. Hawranek,
R Jahn,
V. Jha,
K. Kilian,
S. Kliczewski,
D. Kirillov, [......],
P. von Rossen,
B. J. Roy,
I. Sitnik,
R. Siudak,
M. Smiechowicz,
H. J. Stein,
R. Tsenov,
M. Ulicny,
J. Urban, G. Vankova
[show abstract]
[hide abstract]
ABSTRACT: Several processes of meson production in proton-deuteron collisions have been measured simultaneously using a calibrated magnetic spectrograph. Among these processes, the $\eta$ meson is seen clearly as a sharp missing--mass peak on a slowly varying background in the $p+d\to ^3\textrm{He} +X$ reaction. Knowing the kinematics of the other reactions with well determined masses, it is possible to deduce a precise mass for the $\eta$ meson. The final result, $m(\eta)=547.311\pm 0.028 \textrm{(stat)} \pm 0.032 \textrm{(syst) MeV/c}^2$, is significantly lower than that found by the recent NA48 measurement, though it is consistent with values obtained in earlier counter experiments.
06/2005;
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M Abdel-Bary,
A Budzanowski,
A Chatterjee,
J Ernst,
R Gebel,
P Hawranek,
R Jahn,
V Jha,
K Kilian,
S Kliczewski, [......],
D Proti,
P Von Rossen,
B J Roy,
I Sitnik,
R Siudak,
R Tsenov,
M Ulicny,
J Urban, G Vankova,
C Wilkin
[show abstract]
[hide abstract]
ABSTRACT: Measurement of the d + d → 4 He + η reaction using vector and tensor polarised beam has been performed at COSY using Big Karl magnetic spectrograph. The beam polarisation necessary for obtaining the vector and tensor analysing power for this reaction was measured. The method and the results of the tensor polarisation measurement of the deuteron beam are presented.
01/2002;
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R. Siudak,
A. Budzanowski,
A. Chatterjee,
H. Clement,
E. Dorochkevitsch,
J. Ernst,
P. Hawranek,
F. Hinterberger,
R. Jahn,
L. Jarczyk, [......],
B. Roy,
I. Sitnik,
I. Slepnev,
J. Smyrski,
R. Tsenov,
K. Ulbrich,
J. Urban, G. Vankova,
G.J. Wagner,
R. Ziegler
[show abstract]
[hide abstract]
ABSTRACT: A new threshold Cherenkov detector has been built for the detection of charged pions in the focal plane of a magnetic spectrograph. Silica aerogel with refractive index of n=1.05 is applied as a radiator. The detector exhibits a very high detection efficiency for pions with momenta . Using two Cherenkov detectors in series a very high pion suppression factor of 105 was achieved.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 596(3):311-316. · 1.21 Impact Factor
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A. Budzanowski,
A. Chatterjee,
P. Hawranek,
F. Hinterberger,
R. Jahn,
V. Jha,
K. Kilian,
Da. Kirillov,
Di. Kirillov,
S. Kliczewski, [......],
J. Ritman,
P. von Rossen,
B. J. Roy,
I. Sitnik,
R. Siudak,
H. J. Stein,
R. Tsenov,
J. Urban, G. Vankova,
C. Wilkin
[show abstract]
[hide abstract]
ABSTRACT: Inclusive measurements of pion production in proton-proton collisions in the forward direction were undertaken at 400 and 600 MeV at the cooler synchrotron (COSY) at Forschungszentrum Julich using the Big Karl spectrograph. The high resolution in the π+ momentum ensured that there was an unambiguous separation of the pp→π+d/π+pn channels. Using these and earlier data, the ratio of the production cross sections could be followed through the Δ region and compared with the predictions of final state interaction theory. Deviations are strongly influenced by long-range terms in the production operator and the tensor force in the final pn system. These have been investigated in a realistic pp→π+d/π+pn calculation that includes S⇌D channel coupling between the final nucleons. A semiquantitative understanding of the observed effects is achieved.
Phys. Rev. C. 79(6).
-
A. Budzanowski,
A. Chatterjee,
P. Hawranek,
R. Jahn,
V. Jha,
K. Kilian,
S. Kliczewski,
Da. Kirillov,
Di. Kirillov,
D. Kolev, [......],
N. Piskunov,
D. Protić,
J. Ritman,
P. von Rossen,
B. J. Roy,
I. Sitnik,
R. Siudak,
R. Tsenov,
J. Urban, G. Vankova
[show abstract]
[hide abstract]
ABSTRACT: The cross section for the reaction p+6Li→η+7Be was measured at an excess energy of 11.28 MeV above threshold by detecting the recoiling 7Be nuclei. A dedicated set of focal plane detectors was built for the magnetic spectrograph Big Karl and was used for identification and four-momentum measurement of 7Be. A differential cross section of dσ/dΩ=[0.69±0.20(stat.)±0.20(syst.)] nb/sr for the ground state plus 1/2- was measured. The result is compared to model calculations.
Phys. Rev. C. 82(4).
-
A. Budzanowski,
A. Chatterjee,
R. Gebel,
P. Hawranek,
R. Jahn,
V. Jha,
K. Kilian,
S. Kliczewski,
Da. Kirillov,
Di. Kirillov, [......],
D. Protić,
J. Ritman,
P. von Rossen,
B.J. Roy,
I. Sitnik,
R. Siudak,
R. Tsenov,
J. Urban, G. Vankova,
C. Wilkin
[show abstract]
[hide abstract]
ABSTRACT: The angular distributions of the unpolarised differential cross section and tensor analysing power Axx of the reaction have been measured at an excess energy of 16.6 MeV. The ambiguities in the partial-wave description of these data are made explicit by using the invariant amplitude decomposition. This allows the magnitude of the s-wave amplitude to be extracted and compared with results published at lower energies. In this way, firmer bounds could be obtained on the scattering length of the ηα system. The results do not, however, unambiguously prove the existence of a quasi-bound ηα state.
Nuclear Physics A.
