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input.ampt
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200 ! EFRM (sqrt(S_NN) in GeV if FRAME is CMS)
CMS ! FRAME
A ! PROJ
A ! TARG
197 ! IAP (projectile A number)
79 ! IZP (projectile Z number)
197 ! IAT (target A number)
79 ! IZT (target Z number)
1 ! NEVNT (total number of events)
0. ! BMIN (mininum impact parameter in fm)
3. ! BMAX (maximum impact parameter in fm, also see below)
4 ! ISOFT (D=4): select Default AMPT or String Melting(see below)
150 ! NTMAX: number of timesteps (D=150), see below
0.2 ! DT: timestep in fm (hadron cascade time= DT*NTMAX) (D=0.2)
0.55 ! PARJ(41): parameter a in Lund symmetric splitting function
0.15 ! PARJ(42): parameter b in Lund symmetric splitting function
1 ! (D=1,yes;0,no) flag for popcorn mechanism(netbaryon stopping)
1.0 ! PARJ(5) to control BMBbar vs BBbar in popcorn (D=1.0)
1 ! shadowing flag (Default=1,yes; 0,no)
0 ! quenching flag (D=0,no; 1,yes)
2.0 ! quenching parameter -dE/dx (GeV/fm) in case quenching flag=1
2.0 ! p0 cutoff in HIJING for minijet productions (D=2.0)
2.265d0 ! parton screening mass in fm^(-1) (D=2.265d0), see below
0 ! IZPC: (D=0 forward-angle parton scatterings; 100,isotropic)
0.33d0 ! alpha in parton cascade (D=0.33d0), see parton screening mass
1d6 ! dpcoal in GeV
1d6 ! drcoal in fm
0 ! ihjsed: take HIJING seed from below (D=0)or at runtime(11)
13150909 ! random seed for HIJING
8 ! random seed for parton cascade
0 ! flag for K0s weak decays (D=0,no; 1,yes)
1 ! flag for phi decays at end of hadron cascade (D=1,yes; 0,no)
0 ! flag for pi0 decays at end of hadron cascade (D=0,no; 1,yes)
0 ! optional OSCAR output (D=0,no; 1,yes; 2&3,more parton info)
0 ! flag for perturbative deuteron calculation (D=0,no; 1or2,yes)
1 ! integer factor for perturbative deuterons(>=1 & <=10000)
1 ! choice of cross section assumptions for deuteron reactions
-7. ! Pt in GeV: generate events with >=1 minijet above this value
1000 ! maxmiss (D=1000): maximum # of tries to repeat a HIJING event
3 ! flag on initial and final state radiation (D=3,both yes; 0,no)
1 ! flag on Kt kick (D=1,yes; 0,no)
0 ! flag to turn on quark pair embedding (D=0,no; 1,yes)
7., 0. ! Initial Px and Py values (GeV) of the embedded quark (u or d)
0., 0. ! Initial x & y values (fm) of the embedded back-to-back q/qbar
1, 5., 0. ! nsembd(D=0), psembd (in GeV),tmaxembd (in radian).
0 ! Flag to enable users to modify shadowing (D=0,no; 1,yes)
1.d0 ! Factor used to modify nuclear shadowing
0 ! Flag for random orientation of reaction plane (D=0,no; 1,yes)
%%%%%%%%%% Further explanations:
BMAX: the upper limit HIPR1(34)+HIPR1(35)=19.87fm (dAu), 25.60fm(AuAu).
ISOFT: 1 Default,
4 String Melting.
PARJ(41) & (42): for string melting AMPT, 0.55 & 0.15/GeV^2 are recommended
for top RHIC energies and 0.30 & 0.15/GeV^2 are recommended for
LHC energies (see arXiv:1403.6321 for details).
NTMAX: number of time-steps for hadron cascade.
Use a large value (e.g. 1000) for LHC studies or HBT studies at RHIC.
Using NTMAX=2 or 3 effectively turns off hadronic cascade.
parton screening mass (in 1/fm): its square is inversely proportional to
the parton cross section. Use D=2.265d0 for 3mb cross section
when alpha in parton cascade is set to 0.33;
(note: 3.2264d0 for 3mb cross section when alpha is set to 0.47).
Using 1d4 effectively turns off parton cascade.
ihjsed: if =11, take HIJING random seed at runtime so that
every run may be automatically different (see file 'exec').
iksdcy: flag for K0s weak decays for comparison with data.
iphidcy: flag for phi meson decays at the end of hadron cascade for comparison
with data; default is yes; use 0 to turn off these decays.
Note: phi meson decay during hadron cascade is always enabled.
ipi0dcy: flag for pi0 electromagnetic decays at the end of hadron cascade for
comparison with data; set to 1 to turn on pi0 decays.
ioscar: 0 Dafault,
1 Write output in the OSCAR format,
2 Write out the complete parton information
(ana/parton-initial-afterPropagation.dat)
right after string melting (before parton cascade),
3 Write out several more files on parton information (see readme).
idpert: flag for perturbative deuteron and antideuteron calculations
with results in ana/ampt_pert.dat:
0 No perturbative calculations,
1 Trigger a production of NPERTD perturbative deuterons
in each NN collision,
2 Trigger a production of NPERTD perturbative deuterons only in
an NN collision where a conventional deuteron is produced.
Note: conventional deuteron calculations are always performed
with results in ana/ampt.dat.
NPERTD: number of perturbative deuterons produced in each triggered collision;
setting it to 0 turns off perturbative deuteron productions.
idxsec: choose a cross section model for deuteron inelastic/elastic collisions:
1: same |matrix element|**2/s (after averaging over initial spins
and isospins) for B+B -> deuteron+meson at the same sqrt(s);
2: same |matrix element|**2/s for B+B -> deuteron+meson
at the same sqrt(s)-threshold;
3: same |matrix element|**2/s for deuteron+meson -> B+B
at the same sqrt(s);
4: same |matrix element|**2/s for deuteron+meson -> B+B
at the same sqrt(s)-threshold;
1 or 3 also chooses the same cross section for deuteron+meson or baryon
elastic collision at the same sqrt(s);
2 or 4 also chooses the same cross section for deuteron+meson or baryon
elastic collision at the same sqrt(s)-threshold.
%%%%%%%%%% For jet studies:
pttrig: generate events with at least 1 initial minijet parton above this Pt
value, otherwise repeat HIJING event until reaching maxmiss tries;
use a negative value to disable this requirement and get normal events.
maxmiss: maximum number of tries for the repetition of a HIJING event to obtain
a minijet above the Pt value of pttrig; increase maxmiss if some events
fail to generate at least 1 initial minijet parton above pttrig.
it is safer to set a large value for high pttrig and/or large b value
and/or smaller colliding nuclei.
IHPR2(2): flag to turn off initial and final state radiation:
0 both radiation off, 1 only final off, 2 only initial off, 3 both on.
IHPR2(5): flag to turn off Pt kick due to soft interactions: 0 off, 1 on.
Setting both IHPR2(2) and IHPR2(5) to zero makes it more likely to
have two high-Pt minijet partons that are close to back-to-back.
%%%%%%%%%% To embed a back-to-back light q/qbar jet pair
%%%%%%%%%% and a given number of soft pions along each jet into each event:
iembed: flag to turn on quark pair embedding:
1: on with fixed position(xembd,pembd) and Pt(pxqembd,pyqembd);
2: on with fixed position(xembd,pembd) and random azimuthal angle
with Pt-magnitude given by sqrt(pxqembd^2+pyqembd^2);
3: on with random position and fixed Pt(pxqembd,pyqembd);
4: on with random position and random random azimuthal angle
with Pt-magnitude given by sqrt(pxqembd^2+pyqembd^2);
for iembed=3 or 4: need a position file "embed-jet-xy.txt";
Other integers: off.
pxqembd, pyqembd: sqrt(pxqembd^2+pyqembd^2) > 70MeV/c is required;
the embedded quark and antiquark have pz=0.
xembd, yembd: the embedded quark and antiquark jets have z=0 initially. Note:
the x-axis is defined as the direction along the impact parameter.
nsembd: number of soft pions to be embedded with each high-Pt parton
in the embedded jet pair.
psembd: Momentum of each embedded soft pion in GeV.
tmaxembd: maximum angle(rad) of embedded soft pions relative to high-Pt parton.
%%%%%%%%%% User modification of nuclear shadowing:
ishadow: set to 1 to enable users to adjust nuclear shadowing
provided the shadowing flag IHPR2(6) is turned on; default value is 0.
dshadow: valid when ishadow=1; this parameter modifies the HIJING shadowing
parameterization Ra(x,r)==1+fa(x,r) via Ra(x,r)==1+fa(x,r)*dshadow,
so the value of 0.d0 turns off shadowing
and the value of 1.d0 uses the default HIJING shadowing;
currently limited to 0.d0<=dshadow<=1.d0 to make sure Ra(x,r)>0.
iphirp: set to 1 to turn on random orientation of reaction plane (D=0)