FSoRT

Fluka Simulation of the RAL/LBNF Target

This contains FLUKA input files and user routines for simulating various RAL designs for the LBNF/DUNE target and first magnetic focusing horn system.

Conceptual graphite target designs

1. LongTargetDS.inp : 2.2 m long single downstream (DS) supported target
2. DoubleTarget.inp : two 1 m long targets, including downstream He gas cone
3. SingleTarget.inp : 1.5 m long single target, no downstream support

For these, the Horn A magnetic field is implemented using the usermvax/map_magfld.f code, which must be renamed as magfld.f before running the commands in linkField_INFN.txt, along with usermvax/fieldarray.inc and the field map data stored in FieldMap3D.dat (after it's unzipped).

Preliminary graphite target designs

1. LBNFTargetL150cm.inp : 1.5 m cantilevered target with Horn A upstream inner conductor cone
2. LBNFTargetL150cmSpacers.inp : based on LBNFTargetL150cm.inp with target spacer supports
3. LBNFTargetL150cmFins.inp : based on LBNFTargetL150cm.inp with target fin supports
4. LBNFTargetL150cmFinsOff1.inp : based on LBNFTargetL150cmFins.inp with off-centred beam (1 sigma)
5. LBNFTargetL150cmFinsOff2.inp : based on LBNFTargetL150cmFins.inp with off-centred beam (2 sigma)
6. LBNFTargetL150cmFinsOff3.inp : based on LBNFTargetL150cmFins.inp with off-centred beam (3 sigma)

For these, the Horn A magnetic field is implemented using the usermvax/magfld.f code, which uses the theoretical function B = 0.02*I/r T (a very good approximation), where I is the horn current (kA) and r is the radius (cm). The current I is set within FieldPars.dat, along with the field direction integer (1 for neutrino running, -1 for anti-neutrino running).

Main baffle

These simulate just the 2.5 m long main graphite baffle that is upstream of the target and horn A region. The beam has a maximum horizontal offset of 2.5 cm.

1. LBNFBaffle.inp : fins with edges that point to the origin; +2 deg phi rotation for usrbin alignment
2. LBNFBaffle_WedgeFins.inp : fins with edges that point to the origin, with no additional phi rotation
3. LBNFBaffle_ParFins.inp : fins with edges that are parallel to their mid-centre radial lines.

Target, Horn and main baffle

The LBNFTgtL150cmFinsBaf.inp file implements the geometry for the 1.5 m long target (with support fins), horn A, bafflet and main baffle.

Processing scripts

The pyDir directory contains a range of python scripts and ROOT code that processes Fluka output files.

CERN and INFN Fluka versions

It is recommended to use the Fluka code from CERN (https://fluka.cern) since this works with a much wider range of compiler options and is not restricted to specific gfortran/system libraries, unlike the case for the INFN version (http://www.fluka.org/fluka.php).

User routines for the CERN version need to go into the installed src/user subdirectory instead of the INFN-named usermvax area. The LBNF horn A magnetic field routine we need is src_user/magfld.f, which is based on the previous INFN usermvax/magfld.f code.

The linkDPMJET_CERN.txt script (run within the src install directory) should be used to create the CERN Fluka executable that includes the horn field as well as enabling DPMJET physics options to provide more precise hadronic interactions and radiation dose calculations.

The linkField_CERN.txt script just links in the horn field routine without DPMJET, which is not recommended.

The previous INFN linking scripts have been renamed linkField_INFN.txt and linkDPMJET_INFN.txt.