The OPAL Discussion Forum

["Adelmann Andreas (PSI)" <andreas.adelmann AT psi.ch>]

From: "Power, John" <JP AT anl.gov>

Subject: benchmark with ASTRA

Date: 29 Sep 2016 15:45:29 CEST

To: "Adelmann Andreas (PSI) [andreas.adelmann AT psi.ch]" <andreas.adelmann AT psi.ch>

Cc: Nicole Neveu <nneveu AT hawk.iit.edu>

Hi Andreas, 

We are trying to benchmark OPAL to ASTRA by exporting the initial distribution that is emitted by OPAL into ASTRA and two questions came up.  ----John

 

[Q1]  I see the opal file defines the zero as the head of the bunch (I assume the head and not the tail). Do you know how the code then defines its phases internally, does it place a reference particle at the barycenter of the bunch or is the first particle taken as reference. In Astra I usually define the reference as the bunch center (I have to physically put the reference there) and therefore all the phase are reference are with respect to the bunch center. IMPACT-T does the same thing (1st particle is t=0 and when we compare the phase we have to properly tweak the phase in IMPACT taking the total emission time. 

 

[Q2]  As a side not I also notice the t,pz phase space is a bit awkward, it has some strange horizontal striation -- this is not a big deal for what we are trying to do for now and might just be coming from the way the random generation is done (maybe it is not fully 2D MC generator).