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0001 \page ExampleUHDR Example UHDR
0002
0003 This example is provided by the Geant4-DNA collaboration
0004 (http://geant4-dna.org).
0005
0006 Any report or published results obtained using the Geant4-DNA software
0007 shall cite the following Geant4-DNA collaboration publications:\n
0008 Med. Phys. 45 (2018) e722-e739\n
0009 Phys. Med. 31 (2015) 861-874\n
0010 Med. Phys. 37 (2010) 4692-4708\n
0011 Int. J. Model. Simul. Sci. Comput. 1 (2010) 157–178\n
0012
0013
0014 ## INTRODUCTION
0015
0016 This example shows how to activate the mesoscopic model in chemistry and
0017 combine with IRT-syn model (https://arxiv.org/abs/2409.11993).
0018 It allows to simulate chemical reactions longtime (beyond 1 us) of post-irradiation.
0019 Important : This example is provided as a prototype. Some mistakes may be present in the code.
0020 We would be happy to hear from you — please don’t hesitate to share your feedback and
0021 let us know about any difficulties you may encounter.
0022
0023 To run the example:
0024 ```
0025 mkdir UHDR-build
0026 cd UHDR-build
0027 cmake ../pathToExamples/UHDR
0028 make
0029 ```
0030
0031 To visualize (only for physical stage)
0032 ```
0033 ./UHDR
0034 ```
0035
0036 In batch mode, the macro beam.in can be used as follows:
0037 ```
0038 ./UHDR beam.in
0039 ```
0040 or
0041 ```
0042 ./UHDR beam.in 123
0043 # 123 is the user's seed number
0044 ```
0045
0046 ## GEOMETRY DEFINITION
0047
0048
0049 The world volume is a simple water box 3.2 x 3.2 x 3.2 um3 for 0.01 Gy of cut-off
0050 absorbed dose and 1.6 x 1.6 x 1.6 um3 for 1 Gy. This example is limited to these geometries.
0051 The choice of simulation volume is a compromise between a sufficient number of chemical species a
0052 nd an achievable computation time.
0053
0054 Two parameters define the geometry :
0055 - the material of the box for the physical stage is water.
0056 - for the chemistry stage, the concentration of scavengers in [mole/l]
0057 is added. This concentration is supposed to have no effect on the
0058 physical stage. pH is defined as scavengers of H3O^1, OH^-1.
0059 In this example, we consider that chemical molecules diffuse and react in a
0060 bounded volume (that is, limited by geometrical boundaries) which is also
0061 the irradiated water box volume of the physical stage.
0062 The bouncing of chemical molecules on the volume border is applied
0063 for both SBS and mesoscopic models.
0064 The bouncing is not applied for the physical stage.
0065
0066 ## PHYSICS LIST
0067
0068 PhysicsList is Geant4 modular physics list using G4EmDNAPhysics_option2
0069 and EmDNAChemistry constructors (the chemistry constructor uses the
0070 Step-by-step method).
0071
0072 ## Beamline Dose Cutoff
0073
0074 A threshold dose value along a beamline in a simulation.
0075 This is the total dose per beamline (across all pulses).
0076 The concept of the dose cutoff is that once the recorded dose exceeds this threshold,
0077 the particle beam is automatically stopped.
0078
0079 ```
0080 /scorer/Dose/cutoff 0.1 Gy
0081 ```
0082
0083 ## CHEMISTRY WORLD
0084
0085 This object is controlled by DetectorContruction. It defines the chemistry volume,
0086 scavengers and pH of water.
0087
0088 This fearture can be set by the following commands:
0089 # pH and Scavenger
0090 ```
0091 /UHDR/env/pH 5.5
0092 ```
0093 # air concentration
0094 ```
0095 /UHDR/env/scavenger O2 21 %
0096 /UHDR/env/scavenger CO2 0.041 %
0097 /UHDR/env/scavenger HCO3m 2.4 uM
0098 ```
0099 ## AN EVENT: PRIMARY GENERATOR
0100
0101 This example utilizes the G4SingleParticleSource.
0102 Each event consists of multiple incident particles.
0103 A large number has been chosen to ensure that the stack remains non-empty until the desired
0104 energy deposition is achieved (which is then converted to a cutoff dose).
0105 With each /run/beamOn command, a group of particles is emitted. The cutoff dose
0106 (dose threshold) determined by users.
0107 The actual dose is calculated based on the real energy deposited in the volume.
0108
0109 ## G-value Scorer
0110
0111 There is one G4MultiFunctionalDetector object which computes the
0112 energy deposition and the number of species along time in order to
0113 extract the G-value:
0114 (Number of species X) / (100 eV of deposited energy).
0115
0116 These two macro commands can be used to control the scoring time:
0117 ```
0118 /scorer/Gvalues/addTimeToRecord 1 ps
0119 # user can select time bin to score G values.
0120 /scorer/Gvalues/nOfTimeBins
0121 # or user can automatically select time bin logarithmically.
0122 ```
0123
0124 ## PULSE ACTION and INTERPULSE ACTION
0125
0126 The time structure can be activated by implementing a delayed time, Δt,
0127 which is sampled from a beamline raw signal of a measured pulse.
0128 Each delayed time is associated with a primary particle and propagates to its corresponding
0129 primary chemical species induced by this primary particle.
0130 These primary chemical species remain inactive until the virtual simulation time matches
0131 their respective delayed time. This process creates a duration for the primary particle train
0132 where their primary chemical species are activated randomly through an experimental beam
0133 current transformation, named "pulse duration".
0134
0135 This fearture can be set by the following commands:
0136
0137 # time structure
0138 ```
0139 /UHDR/pulse/pulseOn true // active the time structure
0140 ```
0141 # push structure file
0142 ```
0143 /UHDR/pulse/pulseFile 1.4us // push structure file
0144 ```
0145 # pulse structure
0146 ```
0147 /UHDR/pulse/multiPulse true // active the multi pulse
0148 /UHDR/pulse/pulsePeriod 10 ms // time between two pulses (DIT)
0149 /UHDR/pulse/numberOfPulse 2 // number of pulses
0150 ```
0151 **Important: the multi-pulse function may produce incorrect results with long pulse structures.**
0152 ## OUTPUT
0153
0154 G-value
0155
0156 ## RELEVANT MACRO COMMANDS AND MACRO FILE
0157
0158 The user macro files are:
0159 - beam.in (default),
0160 - CONV.in (Conventional)
0161 - UHDR.in (Ultra High Dose Rate)
0162 - initialize.in (initialize geo and phys)
0163 - scavengers.in (pH and scavengers are defined)
0164
0165 ## REACTION BUILDER
0166
0167 Reaction lists are collected by builders for specific applications.
0168 - ChemNO2_NO3ScavengerBuilder is to build the reaction list with NO2-/NO3-.
0169 - ChemPureWaterBuilder is to build the reaction list with pH.
0170 - ChemOxygenWaterBuilder is to build the reaction list with ROS.
0171 - ChemFrickeReactionBuilder is to build the reaction list of Fricke Dosimeter.
0172
0173 ## PLOT
0174
0175 The information about all the molecular species is scored in a ROOT
0176 (https://root.cern) ntuple file Dose_xxx.root (xxx is seed number).
0177 The ROOT program plot_time.C
0178 can be used to plot the G values vs time for each species.
0179
0180 Execute plot_time as:
0181 ```
0182 root plot_time.C
0183 ```
0184
0185 or print G values to scorer.txt
0186 ```
0187 root plot_time.C > scorer.txt
0188 ```
0189
0190 The results show the molecular species (G values) as a function of
0191 time (ns).
0192
0193 ## Periodic Boundary Condition (PBC)
0194
0195 The Periodic Boundary Condition is implemented based on https://github.com/amentumspace/g4pbc
0196 to calculate microdosimetry. The periodic boundary condition (PBC) is used to simulate the
0197 behavior of secondary electrons during the physical stage.
0198 When an electron exits an edge of a cubic volume, it re-enters from the opposite edge.
0199 The PBC helps reduce the edge effects in dose calculations for micrometer-sized volumes
0200
0201
0202 The PBC requires a maximum dose (xxx) to abort the event. This to avoid the high energy of
0203 secondary electrons deposit a large energy inside the micro volume.
0204
0205 ```
0206 /scorer/Dose/abortedDose xxx Gy
0207 ```
0208
0209 Use the following command to activate or deactivate PBC.
0210
0211 ```
0212 /UHDR/Detector/PBC true
0213 ```
0214
0215 Contact: H. Tran (tran@lp2ib.in2p3.fr)
0216 CNRS, lp2i, UMR 5797, Université de Bordeaux, F-33170 Gradignan, France