coulomb excitation data analysis codes; gosia 2007 - Physics and ...

etween meshpoints. When starting a new calculation it is wise to halve or double the number of subdivisionsat least once to make sure that convergence is achieved. Refer to the troubleshooting section in this chapter.In this example, the Ge detector definitions file det.gdt has already been provided. (The fitting tutorialin this section gives an example of how to create a detector file.) In order to produce simulated yields, Gosiaonly needs to be told to execute the simulate.inp input file using the commandgosia < simulate.inpThe following output should be generatedOPENED simulate.outIO-num = 22 UNKNOWN FORMATTEDetcWhen the system prompt is returned, an output file simulate.out will be present. Among other data, thesimulated, integrated yields appear at the end of the input. The yield output looks like the following.INTEGRATED RUTHERFORD CROSS SECTION=.9472E+03 FOR EXP. 1INTEGRATED YIELDSEXPERIMENT 1 DETECTOR 1ENERGY RANGE 230.000--- 250.000 MEV SCATTERING ANGLE RANGE 60.000--- 80.000 DEGNI NF II IF YIELD NORMALIZED YIELD5 4 8.0 6.0 0.12033E-08 0.12681E-094 3 6.0 4.0 0.14781E-04 0.15576E-053 2 4.0 2.0 0.64335E-01 0.67797E-022 1 2.0 0.0 0.94893E+01 0.10000E+01********* END OF EXECUTION **********First, the Rutherford cross section is given, integrated over the target thickness as well as the solid angle,in mb•mg/cm 2 . To obtain the usual Rutherford cross section, it is necessary to divide this number by thetarget thickness, givingσ R =(0.9472E +03mb•mg/cm 2 )/(0.62mg/cm 2 ) = 1528mb. The cross section for measuring the gammaraytransition from state 2 to state 1 in a perfect (blackbody) detector can be obtained from the finalline of output. In the YIELD column, Gosia gives a differential cross section, which is integrated over theparticle detector solid angle and the energy range in the target, but not over the Ge detector solid angle.In the present example, this quantity is dσ/dΩ γ =(0.94893E + 01)mb•(mg/cm2)(1/sr). The det.gdt filethat came with simulate.inp represents a Ge detector of 5 cm diameter placed with its face 15 cm from thetarget position. Hence, it subtends a solid angle of 0.087sr. (Refer to the second demo on fitting matrixelements for an example that shows how to define a Ge detector.) The absolute cross section for scatteringof the beam into the particle detector and emission of the 2 + to 0 + γ−ray into the Ge detector is thenσ pγ =0.94893E +01mb•(mg/cm2)(1/sr) × 0.087sr ÷ 0.62mg/cm 2 =1.33mb. Note that this is not a pointcalculation of the mean cross section at the mean beam energy, but rather, it is integrated over the energyrange of the beam in the target. Refer to section 5.12.5 of this manual to convert this cross section toabsolute counts.158