KVElasticScatter Class Reference

Detailed Description

Calculate elastic scattering spectra in specific detectors of a multidetector array ,.

KVElasticScatter can be used to simulate elastic and inelastic scattering of projectile nuclei in experimental targets, and calculate the energy spectra of the scattered projectile- or target-like nuclei in all detectors on a given trajectory through the array.

See also

KVElasticCountRates

To begin, build the geometry of the multidetector array for a given dataset:

KVMultiDetArray::MakeMultiDetector("name_of_dataset")

Then initialise a KVElasticScatter with the required run number which will be used to define the default kinematics and the target properties (for energy loss calculations before and after the scattering occurs), e.g.

KVElasticScatter es(31);

To define the trajectory for the scattering, give the name of a detector in the array:

es.SetDetector("SI2-111");
Info in <SetDetector>: Using trajectory: CSI-111/SI2-111/SI1-111/

All particles in the simulation will be scattered into random \(\theta,\phi\) angles corresponding to the direction of these detectors.

Call the Print() method to see the current definitions that will be used by the simulation:

es.Print();
 
Info in <Print>: CALCULATION DETAILS:
Info in <Print>: Entrance channel is: 12C + 1H 11.0 MeV/A
Info in <Print>: Target used is:
Target CH2[193], Target for experiment
Collection name='KVSeqCollection_1269', embedded list class='TList', size=1
 KVMaterial: Polyethylene (CH2)
 Thickness 0.000205319 cm
 Area density 0.000193 g/cm**2
-----------------------------------------------
 Z = 2.66667 atomic mass = 4.66667
 Density = 0.94 g/cm**3
-----------------------------------------------
Info in <Print>: Scattering will be calculated for outgoing PROJECTILE_LIKE
Info in <Print>: We will use the HIGH ENERGY kinematic solutions
Info in <Print>: Particles scattered towards SI2-111: theta:[3.330839,5.169196] phi:[22.297653,46.662894]

If all is correct, run the simulation for a given number of events by calling:

es.CalculateScattering(1000);

Afterwards, you can retrieve the histograms of energy loss in each of the detectors on the chosen trajectory using the label (not the type) of each detector:

es.GetEnergy("SI1")->GetMean();
(double) 120.07858
es.GetEnergy("SI2")->Draw();

etc. etc.

Setting/changing the target nucleus for the kinematics

In the previous example with a carbon beam and polyethylene target, you can see that of the two possible target nuclei in this compound target, it is the protons which are used by default: this has been defined for the systemm corresponding to the chosen run in the database. If you want to change the target nucleus to use for the kinematics, for example to scatter on carbon nuclei, do

es.SetTargetNucleusForScattering("12C");

You can call the Print() method at any moment to check the updated details of the simulation:

es.Print();
 
Info in <Print>: CALCULATION DETAILS:
Info in <Print>: Entrance channel is: 12C + 12C 11.0 MeV/A
...

If the physical target for the chosen run has several layers, by default the scattering will take place in different layers from one event to the next. In this case a different target nucleus can be used for each scattering, depending on the interaction point in the target, if you call:

es.GetTargetNucleusFromTargetLayer(kTRUE);
es.Print()
 
Info in <Print>: CALCULATION DETAILS:
Info in <Print>: Projectile is 12C 11.0 MeV/u; target nucleus depends on scattering layer.

Note

In this case, each layer of the target must be made of a single element, not a compound!

Setting/changing the outgoing nucleus of interest

As you can see above, by default the spectra of energy losses in the different detectors are calculated for the outgoing projectile-like nuclei: to change this, i.e. to calculate for outgoing target-like nuclei, do

es.SetNucleusOfInterest(KV2Body::target_like);

Choice of kinematic solution

As also indicated above, in case there are 2 kinematic solutions for the chosen kinematics and lab angle (detector), by default the high-energy solution corresponding to the most forward centre-of-mass angle solution is used. To change, you can do either

es.SetKinematicSolution(KV2Body::low_E_branch);

to use the solution for backward centre-of-mass angles, or

es.SetKinematicSolution(KV2Body::both_branches);

to randomly choose, event by event, one of the two solutions according to the ratio of the corresponding (Rutherford scattering) cross-sections.

Multilayer targets

When multilayer targets are used, the user can restrict the scattering calculation to one specific layer. Energy losses before and after the scattering in the other layers of the target are of course still taken into account. To set the part of the target where scattering takes place use e.g.

es.SetTargetScatteringLayer("Ni")

with the name of the layer you require (this is normally the name of the element making up the layer - see KVTarget for details).

Inelastic scattering

Calculations can also be performed for inelastic scattering e.g. when either the outgoing projectile- or target-like nucleus is left in an excited state (N.B. we still use the Rutherford elastic scattering cross-section for weighting the energy loss distributions). In order to do this, call

es.SetExcitation(4.438);

with the excitation energy after inelastic scattering.

Definition at line 190 of file KVElasticScatter.h.

#include <KVElasticScatter.h>

Inheritance diagram for KVElasticScatter:

Public Member Functions
	KVElasticScatter (Int_t run)
	Default constructor. More...
virtual	~ KVElasticScatter ()
void	CalculateScattering (Int_t N)
	Perform scattering 'N' times. More...
TH1F *	GetDepth ()
	Return pointer to histogram of 'depth' of scattering point in target (in mg/cm2) More...
Int_t	GetEbinning (void)
	Returns the number of bins of the GetEnergy histogram. More...
TH1F *	GetEnergy ()
	Return pointer to energy loss histogram for chosen detector (in MeV) More...
TH1F *	GetEnergy (const Char_t *label)
	Energy loss in detector with given 'label' through which scattered particle passes. More...
TH1F *	GetEnergy (Int_t index)
auto	GetKinematics ()
Int_t	GetNDets () const
	Returns the number of detectors crossed by the scattered particle. More...
void	GetTargetNucleusFromTargetLayer (Bool_t yes=kTRUE)
TH1F *	GetTheta ()
	Return pointer to polar angle distribution of scattered particle (in degrees) More...
void	Print () const
	Print details of calculation to be performed. More...
void	SetBeamDirection (const TVector3 &beam_dir)
void	SetDetector (const Char_t *det)
void	SetDetectorResolution (double fwhm, double eref)
void	SetEbinning (Int_t nbins)
void	SetExcitation (Double_t ex)
void	SetKinematicSolution (KV2Body::kinematic_solution ik)
void	SetNucleusOfInterest (KV2Body::nucleus_of_interest noi)
void	SetOutGoingProjectileLike (const KVNucleus &opl)
void	SetProjectileNucleus (const KVNucleus &pn)
void	SetTargetNucleusForScattering (const KVNucleus &tn)
void	SetTargetScatteringLayer (const Char_t *name)

Constructor & Destructor Documentation

KVElasticScatter()

KVElasticScatter::KVElasticScatter

(

Int_t

run

)

Default constructor.

Definition at line 28 of file KVElasticScatter.cpp.

~ KVElasticScatter()

virtual KVElasticScatter::~ KVElasticScatter ( )

virtual

Member Function Documentation

CalculateScattering()

void KVElasticScatter::CalculateScattering

(

Int_t

N

)

Perform scattering 'N' times.

Definition at line 250 of file KVElasticScatter.cpp.

GetDepth()

TH1F* KVElasticScatter::GetDepth ( )

inline

Return pointer to histogram of 'depth' of scattering point in target (in mg/cm2)

Definition at line 314 of file KVElasticScatter.h.

GetEbinning()

Int_t KVElasticScatter::GetEbinning ( void  )

inline

Returns the number of bins of the GetEnergy histogram.

Definition at line 336 of file KVElasticScatter.h.

GetEnergy() [1/3]

TH1F* KVElasticScatter::GetEnergy ( )

inline

Return pointer to energy loss histogram for chosen detector (in MeV)

Definition at line 319 of file KVElasticScatter.h.

GetEnergy() [2/3]

TH1F * KVElasticScatter::GetEnergy

(

const Char_t *

label

)

Energy loss in detector with given 'label' through which scattered particle passes.

Definition at line 415 of file KVElasticScatter.cpp.

GetEnergy() [3/3]

TH1F * KVElasticScatter::GetEnergy

(

Int_t

index

)

Energy loss in any detector through which scattered particle passes.

The index corresponds to the order in which detectors are crossed by the particle, beginning with 0 for the first detector, and ending with (GetNDets()-1)

Definition at line 432 of file KVElasticScatter.cpp.

GetKinematics()

auto KVElasticScatter::GetKinematics ( )

inline

Definition at line 340 of file KVElasticScatter.h.

GetNDets()

Int_t KVElasticScatter::GetNDets ( ) const

inline

Returns the number of detectors crossed by the scattered particle.

Definition at line 331 of file KVElasticScatter.h.

GetTargetNucleusFromTargetLayer()

void KVElasticScatter::GetTargetNucleusFromTargetLayer ( Bool_t  yes = kTRUE )

inline

Call with yes=kTRUE if you have a multilayer target with random sampling of interaction point, and you want to calculate the scattering from the different target nucleus in each layer.

Note: this will only work if all layers of the target are single elements (i.e. a single type of nucleus in each layer), not compounds.

Definition at line 290 of file KVElasticScatter.h.

GetTheta()

TH1F* KVElasticScatter::GetTheta ( )

inline

Return pointer to polar angle distribution of scattered particle (in degrees)

Definition at line 324 of file KVElasticScatter.h.

Print()

void KVElasticScatter::Print

(

void

)

const

Print details of calculation to be performed.

Definition at line 447 of file KVElasticScatter.cpp.

SetBeamDirection()

void KVElasticScatter::SetBeamDirection ( const TVector3 &  beam_dir )

inline

Use to change alignment of beam (default is {0,0,1})

Definition at line 233 of file KVElasticScatter.h.

SetDetector()

void KVElasticScatter::SetDetector

(

const Char_t *

det

)

Give name of detector towards which elastic scattering will occur.

Note

this does not necessarily mean that the particle will actually arrive in the given detector (it may stop before it), but the aim is to define the trajectory of the particle in the array.

Definition at line 91 of file KVElasticScatter.cpp.

SetDetectorResolution()

void KVElasticScatter::SetDetectorResolution ( double  fwhm, double  eref  )

inline

Use detector resolution (% FWHM) measured for some reference energy [MeV] for calculated spectra.

FWHM for energy E will simply be calculated as sqrt(E/eref)*fwhm

Definition at line 264 of file KVElasticScatter.h.

SetEbinning()

void KVElasticScatter::SetEbinning

(

Int_t

nbins

)

Set binning of the GetEnergy histogram Default value is 500

Definition at line 166 of file KVElasticScatter.cpp.

SetExcitation()

void KVElasticScatter::SetExcitation ( Double_t  ex )

inline

To simulate inelastic scattering use this method to set the total excitation energy (in MeV).

This value will be used for all subsequent calculations.

Use SetExcitation(0) to return to elastic scattering.

Definition at line 275 of file KVElasticScatter.h.

SetKinematicSolution()

void KVElasticScatter::SetKinematicSolution ( KV2Body::kinematic_solution  ik )

inline

Except for projectile-like nuclei in direct kinematics, for almost every other case the kinematics of outgoing nuclei is double-valued, i.e. to each c.m. scattering angle corresponds 2 lab scattering angles, with different energies.

The case with the smallest (most forward) c.m./lab angles is referred to as the 'high energy branch', while the solution at more backward angles has lower energies.

By default we use the high energy branch; you can choose the low energy here.

Definition at line 251 of file KVElasticScatter.h.

SetNucleusOfInterest()

void KVElasticScatter::SetNucleusOfInterest ( KV2Body::nucleus_of_interest  noi )

inline

Define the the nucleus of interest in the outgoing channel of the reaction

PROJECTILE + TARGET -> PROJECTILE_LIKE + TARGET_LIKE

Note that the identity of the outgoing PROJECTILE_LIKE can be changed with method SetOutgoingProjectileLike() which will of course change TARGET_LIKE to conserve mass and charge.

Definition at line 239 of file KVElasticScatter.h.

SetOutGoingProjectileLike()

void KVElasticScatter::SetOutGoingProjectileLike ( const KVNucleus &  opl )

inline

Definition at line 284 of file KVElasticScatter.h.

SetProjectileNucleus()

void KVElasticScatter::SetProjectileNucleus ( const KVNucleus &  pn )

inline

change the default projectile for the reaction

Definition at line 306 of file KVElasticScatter.h.

SetTargetNucleusForScattering()

void KVElasticScatter::SetTargetNucleusForScattering ( const KVNucleus &  tn )

inline

call this method to change the default target nucleus of the kinematics for the run

Definition at line 299 of file KVElasticScatter.h.

SetTargetScatteringLayer()

void KVElasticScatter::SetTargetScatteringLayer

(

const Char_t *

name

)

For multilayer targets, use this method to choose in which layer the scattering will take place.

If name="", reset any previous choice so that scattering can take place in any layer

Definition at line 141 of file KVElasticScatter.cpp.