Generating the free-nucleon splines and then the nuclear splines went OK, but
there are puzzles.
The nu_mu total cross-section goes crazy just above 1500 GeV (see plot). All I
did was modify config/UserPhysicsOptions.xml to have GVLD-Emax = 2000 (GeV), and
use gmkspl with -e 2000 to generate all the splines (freenuc first, then
nuclei). I did not re-build the code, so I still have --enable-vhe-extension.
Looking at the output from this command:
gmkspl -p 12,14,16,-12,-14,-16 -t 1000060120 -e 2000 -o 1000060120.xml
I see many hundreds of errors like this:
1307662008 ERROR GridDim : [n] <UnifGridDimension.cxx::ClosestPoint (109)> :
Non-positive step (=0)
I see many hundreds of warnings like this:
1307662008 WARN FMap : [n] <FunctionMap.cxx::Value (74)> : No point with UId = 8
And I see six errors like this, all for anti-neutrinos:
1307662036 ERROR IntLst : [n]
<QELInteractionListGenerator.cxx::CreateInteractionListCharmCC (206)> :
Returning NULL InteractionList for init-state: nu-pdg:-14;tgt-pdg:1000060120;
Note that I saw similar errors before changing GVLD-Emax to 2000 (i.e. when it
was 300). Moreover, the spline file was written, and seems to work (below 1500 GeV).
Many splines have their last 4 points at E={1290,1493,1728,2000}; some are
E={932,1203,1551,2000}.
Many of the splines seem to be approximately constant in the range 1000<E<2000,
but some are increasing ~ proportional to E. I strongly suspect the problem is
the following splines -- they have their largest value in the next-to-last point
E=1728 and a zero at E=2000, which is surely wrong:
genie::AivazisCharmPXSecLO/CC-Default
/nu:-12;tgt:1000060120;N:2112;q:-1(s);proc:Weak[CC],DIS;charm:incl;
genie::AivazisCharmPXSecLO/CC-Default
/nu:-12;tgt:1000060120;N:2112;q:-3(s);proc:Weak[CC],DIS;charm:incl;
genie::AivazisCharmPXSecLO/CC-Default
/nu:-12;tgt:1000060120;N:2212;q:-1(s);proc:Weak[CC],DIS;charm:incl;
genie::AivazisCharmPXSecLO/CC-Default
/nu:-12;tgt:1000060120;N:2212;q:-3(s);proc:Weak[CC],DIS;charm:incl;
There may be others with this disease, I stopped looking. These are among the
largest cross-sections at E=1728. So it looks like there is a bug that affects
the highest-energy point. Given the nature of cubic splines, it seems reasonable
that this erroneous zero starts affecting the values around E=1500, as in the plot.
I wonder if I can work around this by setting GVLD-Emax to 4000 but only using
it up to 2000 (to get at least 4 points above the highest energy used, so the
value of the highest point is irrelevant). Or is there something more serious
happening?
Does anybody know what is going on?
[On my 4-core Mac Pro, it took 2.5 hours to generate the freenuc
splines (using 3 cores), and then 2 hours to generate splines for
all 6 neutrinos on 143 nuclei (using 4 cores). I put each nucleus
in its own file and have code that only loads spline files for
the nuclei actually used, greatly speeding up initialization.]
Tom Roberts
On 6/9/11 6/9/11 - 3:51 PM, Constantinos Andreopoulos wrote:
> Dear Tom.
>
> On 9 Jun 2011, at 20:55, Tom Roberts<[log in to unmask]> wrote:
>
>> Costas:
>>
>> Thank you. That sounds simple enough.
>>
>> I believe that after changing config/UserPhysicsOptions.xml I must re-generate all of the splines. But the posted gxspl-freenuc-v2.6.2.xml only goes up to 200 GeV. So how do I generate the free nucleon splines? Do I just do this:
>> unset GSPLOAD
>> gmkspl -p 12,14,16,-12,-14,-16 -t 1000000010,1000010010 -e 2000 \
>> -o freenuc-v.2.6.2.xml
>> and then set GSPLOAD=$PWD/freenuc-v.2.6.2.xml for the other targets?
>
> Yes.
>
> Generating the free nucleon splines takes long time (integrating the differential cross section for every modelled process -about 100 or so- for every energy for every initial state).
> What I do is to split the task and submit multiple jobs at a batch farm. Then I combine the XML outputs using the gspladd utility (see manual).
> See in src/scripts/production/batch (or in http://projects.hepforge.org/genie/trac/browser/trunk/src/scripts/production/batch ). The script you want is named submit-xsec_freenuc.pl .
> I am using it at the RAL/PPD Tier2 which is using PBS. But the script also supports LSF so you should be able to adjust it easily and use it at FNAL.
>
> With the gmkspl utility you can use the "-n" option to set the number of knots in each spline. By default gmkspl uses logarithmically spaced knots, starting from the energy threshold of each process. It uses (by default) 15 knots per decade. Use a sensible number to avoid getting an enormous XML file, especially if you plan to add multiple nuclear targets.
>
> cheers
> Costas
>
> --
> Dr Constantinos Andreopoulos
> Staff Scientist
> STFC, Rutherford Appleton Lab
> http://costas.andreopoulos.eu
>
> Sent from my iPhone
>
>
>>
>>
>> Note I will be running Genie for the neutrinos from 2 TeV muon decays, so different neutrino types and energies are all mixed together. (I am interfacing Genie to another simulation program that handles everything except the neutrino interactions, tracking neutrinos with greatly enhanced interaction lengths in regions of interest.)
>>
>>
>> Tom Roberts
>>
>>
>> On 6/9/11 6/9/11 - 1:23 PM, Costas Andreopoulos wrote:
>>> Just increase in the limit at the very end of the config/UserPhysicsOptions.xml .
>>> I do not think that the simulation quality deteriorates very fast in high energies.
>>> Results at ~2 TeV should be sensible. But, I've never run the simulation at 2 TeV.
>>> Let me know if there are problems.
>>>
>>> You don't have to use the --enable-vhe-extension. This is experimental and,
>>> currently, it just adds a Glashow resonance generator (PeV scales).
>>> This option should (but it currently doesn't) adjust the DIS generator for use in higher-energies
>>> (use a lower minimum Bjorken x cutoff value, use a PDF set other than the Bodek-Yang which is tuned
>>> to high-x low-Q2 data, switch-on the propagator term in the DIS cross section etc... ).
>>>
>>> Also if you are running GENIE at 2 TeV then (for reasons of computational efficiency)
>>> you may want to disable all modes other than DIS.
>>>
>>> Best,
>>> Costas
>>>
>>> On 8 Jun 2011, at 22:13, Tom Roberts wrote:
>>>
>>>> I want to investigate neutrino backgrounds from a muon collider, so I need neutrino energies up to about 2 TeV.
>>>>
>>>> What is the status of Genie's very high energy extension? How do I use it?
>>>>
>>>> In my .configure command I included --enable-vhe-extension. But in gmkspl when I try to go above 300 GeV it says "Refusing to exceed validity range: Emax = 300".
>>>>
>>>> As I am investigating backgrounds, I am primarily concerned with the total cross-section, and not the details of the secondaries (as long as they are not crazy). I realize there are no experimental data at such high energies, and there are theoretical uncertainties.
>>>>
>>>> Is there anything simple I can do that will give results up to 2 TeV that aren't crazy (even if they are not known to be accurate)?
>>>>
>>>>
>>>> Tom Roberts
>>>
