The OPAL Discussion Forum

[Van de Walle Jarno <jarno.van.de.walle AT sckcen.be>]

Hello,

 

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 radiasoft.net>
Sent: woensdag 6 april 2022 16:58
To: Van de Walle Jarno <jarno.van.de.walle AT sckcen.be>
Cc: Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch>; opal AT lists.psi.ch
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> * ********************************************************************************** 

 

best,

Chris

 

On Wed, Apr 6, 2022 at 5:35 AM Van de Walle Jarno <jarno.van.de.walle AT sckcen.be> 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

Jarno

 

 

 

 

 

From: Adelmann Andreas (PSI) <andreas.adelmann AT psi.ch>
Sent: woensdag 6 april 2022 12:45
To: Van de Walle Jarno <jarno.van.de.walle AT sckcen.be>
Cc: opal AT lists.psi.ch
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};

STOP;

 

Otherwise I will look at this again.

 

 

 

Cheers Andy 

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On 5 Apr 2022, at 15:52, Van de Walle Jarno <jarno.van.de.walle AT sckcen.be> wrote:

 

Hello,

 

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 …

E.g.:

- 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

 

 

 

Jarno Van de Walle, PhD
Beam physicist

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+32 14 33 84 16 ǀ +32 470 20 98 31

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Belgian Nuclear Research Centre

Boeretang 200 - 2400 Mol – Belgium

www.sckcen.be

 

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