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SUMMARY:STUDY OF NEUTRON REMOVAL MECHANISMS IN THE 9Be(7Be\, 6Be)X REACTIO
 N AT INTERMEDIATE ENERGIES
DTSTART;VALUE=DATE-TIME:20261030T151000Z
DTEND;VALUE=DATE-TIME:20261030T152500Z
DTSTAMP;VALUE=DATE-TIME:20261105T164643Z
UID:indico-contribution-6356@cern.ch
DESCRIPTION:Speakers: Danila Makarov (Flerov Laboratory of Nuclear Reactio
 ns\, JINR\, Dubna\, Russia\; National Research Nuclear University MEPhI\, 
 Moscow\, Russia)\nIn this work\, the population mechanisms of the ^{6}Be n
 uclear states in the ^{9}Be(^{7}Be\, ^{6}Be)X neutron removal reaction at 
 a beam energy of 67 MeV/nucleon are investigated using theoretical models 
 of increasing complexity. The analyzed experimental data were obtained at 
 the National Superconducting Cyclotron Laboratory (NSCL\, MSU\, USA) in 20
 11 and stand out as a record in terms of statistics and detail for radioac
 tive ion beam reaction studies. Previously\, these data were analyzed excl
 usively from the perspective of the ^{6}Be → ^{4}He+p+p decay\, utilizin
 g the simplest "sudden removal approximation"\, where the transition ampli
 tude is expressed via the projectile form factor. However\, this model pro
 ves unsatisfactory as it fails to describe the experimental results even a
 t a qualitative level.\n\nThe simplest model that satisfies energy-momentu
 m conservation and allows for a semi-analytical treatment is the "quasi-fr
 ee scattering" model formulated within the Plane Wave Born Approximation (
 PWBA). This approach describes the scattering of a projectile nucleon on t
 he target nucleus as a whole. To perform a meaningful comparison with expe
 riment\, target thickness effects\, detector geometry constraints\, and in
 elasticity effects in the ^{9}Be+n channel were incorporated into the mode
 l. Nevertheless\, this approximation managed to reproduce only a fraction 
 of the momentum distribution. However\, incorporating absorption in the pa
 rticipant-target channel within the PWBA framework can only reproduce the 
 data using unrealistic model parameters.\n\nFor a complete description of 
 the experimental data\, a new model describing neutron scattering on indiv
 idual target nucleons has been developed\, provisionally named "symmetric 
 quasi-free scattering". When combined with the PWBA formalism and adjusted
  for target thickness and detector array geometry\, this model successfull
 y describes the experimental data with high accuracy for both low-lying an
 d highly excited states. Furthermore\, the data obtained in the same exper
 iment for the two-body decay channel ^{6}Be → ^{3}He+^{3}He also demonst
 rate good agreement with this approximation.\n\nThis report presents a com
 parative analysis of the experimental data interpreted within the sudden r
 emoval approximation\, the standard PWBA formalism\, and the "symmetric qu
 asi-free scattering" model for both low-lying and highly excited states in
  the three-body ^{6}Be → ^{4}He+p+p decay channel. Additionally\, simula
 tion results obtained using the "symmetric quasi-free scattering" model an
 d the PWBA formalism for the two-body ^{6}Be → ^{3}He+^{3}He decay chann
 el are demonstrated.\n\nReferences\n1. L. V. Grigorenko et al. Phys. Lett.
  B 677\, 30–35 (2009).\n2. I. A. Egorova et al. Phys. Rev. Lett. 109\, 2
 02502 (2012).\n3. L. V. Grigorenko et al. Phys. Rev. C 80\, 034602 (2009).
 \n\nhttps://indico.particle.mephi.ru/event/626/contributions/6356/
LOCATION: Conference Hall 1
URL:https://indico.particle.mephi.ru/event/626/contributions/6356/
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