Cross Section and Tensor Analysing Power of the dd ---> eta alpha Reaction Near Threshold

The GEM collaboration Budzanowski, A. ; Chatterjee, A. ; Gebel, R. ; et al.
Nucl.Phys. A821 (2009) 193-209, 2009.
Inspire Record 803178 DOI 10.17182/hepdata.52401

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.

3 data tables

Total cross section from fit to the differential angular distribution.

Differential angular distribution.

Analysing power measurements.


Differential cross-sections measurement for the p p ---> d pi+ reaction at 850-MeV/c

The GEM collaboration Betigeri, M. ; Bojowald, J. ; Budzanowski, A. ; et al.
Phys.Rev. C63 (2001) 044011, 2001.
Inspire Record 551879 DOI 10.17182/hepdata.54884

The present data support a large anisotropy in accordance with phase shift predictions and in contrast to another recent experiment.

4 data tables

Measured deuteron angular distribution in the c.m. system. The errors shown are statistical only and there is an additional 10 PCT systematic uncertainty on the overall normalisation.

Legendre polynomial coefficients from a second order and fourth order fit.

Total cross section from second order fit.

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Measurement of p d ---> He-3 eta in S(11) resonance

The GEM collaboration Betigeri, M. ; Bojowald, J. ; Budzanowski, A. ; et al.
Phys.Lett. B472 (2000) 267-272, 2000.
Inspire Record 511291 DOI 10.17182/hepdata.31344

We have measured the reaction p + d -> 3He + eta at a proton beam energy of 980 MeV, which is 88.5 MeV above threshold using the new ``germanium wall'' detector system. A missing--mass resolution of the detector system of 2.6% was achieved. The angular distribution of the meson is forward peaked. We found a total cross section of (573 +- 83(stat.) +- 69(syst.))nb. The excitation function for the present reaction is described by a Breit Wigner form with parameters from photoproduction.

1 data table

No description provided.


Total and differential cross-sections of p + p ---> pi+ + d reactions down to 275-keV above threshold

The GEM collaboration Drochner, M. ; Ernst, J. ; Fortsch, S ; et al.
Phys.Rev.Lett. 77 (1996) 454-457, 1996.
Inspire Record 431032 DOI 10.17182/hepdata.19580
1 data table

The CONST is p-wave contribution to the cross section. The differential cross section is fitted usig the relations 4*pi*D(SIG)/D(OMEGA) = SIG + CONST*P2(COS(THETA)), where P2 denotes the Legendre polynomial.