Electromagnetic dissociation of relativistic ²⁸Si by nucleon emission

Thesis/Dissertation · Tue Dec 01 04:00:00 EST 1992

DOI:https://doi.org/10.2172/10136495· OSTI ID:10136495

Sonnadara, Upal Jayasiri ^[1]

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1. Univ. of Pittsburgh, PA (United States)

A detailed study of the electromagnetic dissociation of ²⁸Si by nucleon emission at E_lab/A = 14.6 (GeV/nucleon was carried out with ²⁸Si beams interacting on ²⁰⁸Pb). ¹²⁰Sn. ⁶⁴C targets. The measurements apparatus consists of detectors in the target area which measure the energy and charged multiplicity, and a forward spectrometer which measures the position, momentum and energy of the reaction fragments. The exclusive electromagnetic dissociation cross sections for decay channels having multiple nucleons in the final state have been measured which enables the selection of events produced in pure electromagnetic interactions. The measured cross sections agree well with previous measurements obtained for the removal of a few nucleons as well as with measurements on total charge removal cross sections from other experiments. The dependence of the integrated cross sections on the target charge Z_T and the target mass AT confirms that for higher Z targets the excitation is largely electromagnetic. Direct measurements of the excitation energy for the electromagnetic dissociation of ²⁸Si → p+²⁷Al and ²⁸Si → n+²⁷Si have been obtained through a calculation of the invariant mass in kinematically, reconstructed events. The excitation energy spectrum for all targets peak near the isovector giant dipole resonance in ²⁸Si. These distributions are well reproduced by combining the photon spectrum calculated using the Weizsaecker-Williams approximation with the experimental data on the photonuclear ²⁸Si(_γ,p)²⁷Al and ²⁸Si(_γ,n)²⁷Si. The possibilities of observing double giant dipole resonance excitations in ²⁸Si have been investigated with cross section measurements as well as with excitation energy reconstruction.

• Research Organization: Pittsburgh Univ., PA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: FG02-87ER40363
• OSTI ID: 10136495
• Report Number(s): DOE/ER/40363--T3; ON: DE93008670
• Country of Publication: United States
• Language: English

Related Subjects

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
A = 190-219
A = 20-38
A = 59-89
A = 6-19
A = 90-149
ALUMINIUM 27
ALUMINIUM 27 TARGET
CARBON 12 TARGET
COPPER 64 TARGET
COULOMB SCATTERING
CROSS SECTIONS
DISSOCIATION
EXPERIMENTAL DATA
GEV RANGE 100-1000
GIANT RESONANCE
HEAVY-ION-INDUCED REACTIONS AND SCATTERING
LEAD 208 TARGET
NEUTRONS
PROTONS
RELATIVISTIC RANGE
SILICON 27
SILICON 28 REACTIONS
TIN 120 TARGET