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RE: [Opal] beamline simulation for low energy radioactive ion beams

Chronological Thread  
  • From: Van de Walle Jarno < AT>
  • To: Chris Hall <chall AT>
  • Cc: "Adelmann Andreas (PSI)" <andreas.adelmann AT>, "opal AT" <opal AT>
  • Subject: RE: [Opal] beamline simulation for low energy radioactive ion beams
  • Date: Thu, 7 Apr 2022 14:48:21 +0000
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Indeed that SIGMAPX and SIGMAPY parameters were completely off. Thanks for this, it makes sense now.

Actually, I didn’t pay attention to the DISTRIBUTION line, since I converted my MADX file through SIREPO to an OPAL input file.

I had to clean the input file a bit, but I skipped the –rather crucial-  DISTRIBUTION line … My mistake.


Thanks for the support in any case!

Wbr - Jarno




From: Chris Hall <chall AT>
Sent: woensdag 6 april 2022 16:58
To: Van de Walle Jarno < AT>
Cc: Adelmann Andreas (PSI) <andreas.adelmann AT>; opal AT
Subject: Re: [Opal] beamline simulation for low energy radioactive ion beams


Hi Jarno,


Have you checked the momentum spread values in your distribution command? They seem like they could be too large.


The spreads in momenta: SIGMAPX and SIGMAPY are beta * gamma ~ 1.9e-2 while the ion you define with kinetic energy of 60 keV would have beta * gamma ~ 0.001135


Reducing SIGMAPX and SIGMAPY and rerunning your file does give the expected result.


OPAL> * ************** B U N C H *********************************************************
OPAL> * NP              = 10
OPAL> * Qtot            =          nan [fC]         Qi    =          nan [fC]
OPAL> * Ekin            =      60.000 [keV]         dEkin =      125.005 [eV]
OPAL> * rmax            = (      0.00577 ,      0.00934 ,      1.41280 ) [m]
OPAL> * rmin            = (     -0.00652 ,     -0.00590 ,     -1.83719 ) [m]
OPAL> * rms beam size   = (      3.92589 ,      5.05274 ,    876.44496 ) [mm]
OPAL> * rms momenta     = (  1.74034e-05 ,  2.00784e-05 ,  1.11049e-06 ) [beta gamma]
OPAL> * mean position   = (      0.00000 ,      0.00000 ,      0.00000 ) [um]
OPAL> * mean momenta    = ( -1.35525e-21 ,  6.77626e-22 ,  1.13470e-03 ) [beta gamma]
OPAL> * rms emittance   = (  3.69485e-05 ,  4.72728e-05 ,  8.13134e-04 ) (not normalized)
OPAL> * rms correlation = (  7.89465e-01 ,  8.48699e-01 ,  3.17525e-01 )
OPAL> * hr              = (      0.81947 ,      1.01585 ,    104.83819 ) [mm]
OPAL> * dh              =   1.00000e-10 [%]
OPAL> * t               =        0.000 [fs]         dT    =        1.000 [ns]
OPAL> * spos            =        0.000 [um]
OPAL> * ********************************************************************************** 





On Wed, Apr 6, 2022 at 5:35 AM Van de Walle Jarno < AT> wrote:

Hello Andreas,


Thanks for your quick reply!


There seems indeed some misinterpretation of restmass and kinetic or total energy …


The restmass for an ion of mass 100 (say, for ease we consider Sn-100) is than 100*amu = 93149.41 MeV

The kinetic energy is only 0.06 MeV

Total energy follows naturally.

Gamma = 1.0000006441

B.rho = 0.352663 T.m

These values are correct in the input file.


So in the ‘BEAM’ statement I :

- omit the PARICLE definition (since it’s none of the predefined symbolic constants). When running OPAL notifies it’s assigning ‘UNNAMED’

- MASS = rest mass, correct ? Not total mass ?

- CHARGE = 1+

- BEAM ENERGY I specify as GAMMA (since it has highest priority, as read from paragraph 14.1 in the manual)

- BFREQ I assigned according to your suggestion (although we have a continuous beam here, but I suppose this doesn’t really affect the tracking ?)

- BCURRENT = 1e-6


When running like this, I get:

=> Momentum is zero ?


And weird Ekin and dEkin definitions in “BUNCH” output


Can the code really be used for none predefined particles, like I try to do here ?


Many thanks in advance for any further assistance!

With kind regards







From: Adelmann Andreas (PSI) <andreas.adelmann AT>
Sent: woensdag 6 april 2022 12:45
To: Van de Walle Jarno < AT>
Cc: opal AT
Subject: Re: [Opal] beamline simulation for low energy radioactive ion beams


Hi Jarno you need to define the charge for example 



REAL f1   = 50.65;  // MHz 



"RIB": BEAM, MASS=E0*1e-3, charge=1.0, ENERGY=E_TOT*1e-3, npart=10.0, BCURRENT=1.0E-6, BFREQ= f1;



Still, something seams to be off with the rest-mass. Consider to check by printing some values like:


value, {sr_gamma, E0};



Otherwise I will look at this again.




Cheers Andy 

Dr. sc. math. Andreas (Andy) Adelmann
Head a.i. Labor for Scientific Computing and Modelling 
Paul Scherrer Institut OHSA/ CH-5232 Villigen PSI
Phone Office: xx41 56 310 42 33 Fax: xx41 56 310 31 91
Zoom ID: 470-582-4086 Password: AdA

Zoom Link:

Friday: ETH HPK G 28   +41 44 633 3076
The more exotic, the more abstract the knowledge, 
the more profound will be its consequences.
Leon Lederman 


On 5 Apr 2022, at 15:52, Van de Walle Jarno < AT> wrote:




I’m new to OPAL and I’m trying to simulate a beamline for radioactive ions, which I did in MAD-X, now in OPAL.

The properties of the beam are:

Mass = 100 (amu)

Energy = 60 keV (!)

The beamline consists of 4 quad doublets and 1 dipole (112 degrees).

In MAD-X this runs smoothly and I wanted to check first of all if I can get similar results with OPAL. The next step would be to include a real 3D magnetic field map for the dipole in OPAL (which is not possible in MAD-X).


The first results are not encouraging L

I encounter multiple issues – which are probably related to a misinterpretation of the input file needs …


- when including the dipole, the tracking takes way too long to be realistic (so somewhere the tracking blocks)

- If I exclude the dipole (like in the attached inputfile), I see that The Kinetic energy of the beam is suddenly 4.528 GeV with dE = 19.686 MeV ?! No idea why …


I’m in any case convinced that OPAL could help us further in the simulation of our Radioactive Ion Beam beamlines and in the future our 100 MeV proton accelerator.

May I ask you to run the attached input file and/or hint towards my (obvious, maybe J) mistakes ?


Any help is highly appreciated !

Many thanks in advance and kind regards





Jarno Van de Walle, PhD
Beam physicist


+32 14 33 84 16 ǀ +32 470 20 98 31




Belgian Nuclear Research Centre

Boeretang 200 - 2400 Mol – Belgium






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