Message: neutron at rest decay Not Logged In (login)
 Next-in-Thread Next-in-Thread
 Next-in-Forum Next-in-Forum

Question neutron at rest decay 

Keywords: neutron at rest decay
Forum: Event and Track Management
Date: 04 Nov, 2004
From: Emil Frlez <Emil Frlez>

 Dear GEANT4 practitioners,

 I have a problem decaying neutrons.
 I am interested in simulating the beta decay of neutron 
 at rest: n -> p e- nu

 I use examples/extended/electromagnetic/TestEm5
 as a template.

 OK, in order to set the global time at zero at decay I
 set the neutron lifetime to a very small value:

/particle/select neutron /particle/property/stable false /particle/property/lifetime 1.E-20

 It works and my neutron decays essentially instantaneously.

 The problem is, the final-state proton is never tracked, 
 actually it never appears as a decay product at all if the
 initial neutron kinetic energy is zero. The electron
 and neutrino are handled correctly and appear on the stack.
 I check it by printing the global times, energies, particles'
 ID from the SteppingAction.cc

 Only if I set the initial neutron kinetic energy to 
 non-zero, proton appears.

 I have the following user cuts in DetectorConstruction

G4double theMaxStepSize = 0.1 * mm; G4double theMaxTime = 0.001 * s; G4double theMinEkine = 1.0 * eV;

logicWorld->SetUserLimits
 (new G4UserLimits(theMaxStepSize,
                   DBL_MAX,        // theMaxLengthCut
                   theMaxTime,        // theMaxTimeCut
                   theMinEkine)); 

 I check that if a particle selected in the PrimaryGeneratorEvent.cc
 is the proton, it is tracked if its kinetic energy is above 1 eV.
 But it is not put on stack if proton_KE< 1 eV, regardless
 of my seting of theMinEkine?

 My question: because in the neutron decay at rest, the proton
 kinetic energy is up to 0.8 keV, why it is NEVER put
 on a stack in the decay process? What is the variable,
 a cut, I am not setting right?

					Cheers, Emil Frlez

Inline Depth:
 1 1
 All All
Outline Depth:
 1 1
 2 2
 All All
Add message: (add)

1 None: Re: neutron at rest decay   (Daniel Barna - 04 Nov, 2004)
(_ Note: Re: neutron at rest decay   (Emil Frlez - 04 Nov, 2004)
(_ Note: Re: neutron at rest decay   (Emil Frlez - 08 Nov, 2004)
1 Feedback: Re: neutron at rest decay   (Peter Gumplinger - 08 Nov, 2004)
3 Agree: Re: neutron at rest decay   (Hisaya Kurashige - 13 May, 2011)
 Add Message Add Message
to: "neutron at rest decay"

 Subscribe Subscribe

This site runs SLAC HyperNews version 1.11-slac-98, derived from the original HyperNews


[ Geant 4 Home | Geant 4 HyperNews | Search | Request New Forum | Feedback ]