[Clas12_verystrange] Omega-

[Michael Dugger]

Igor,

We had a communication problem. I did not understand that you wanted 0.3 
nb in place of the neutral-cascade-cross-section*1/10. The effective 
cross section I use comes out to about 0.36 nb. So I don't think this is 
much of a problem. I will, however start using the 0.3 nb that you 
request.

Take care,
Michael

On Fri, 24 Feb 2012, Igor Strakovsky wrote:

> Folks,
>
> As we discussed before, please use 0.3 nb as total cross section for the
> exclusive Omega- photoproduction
>
> Thanks, Igor
>
> On Fri, 24 Feb 2012 13:18:02 -0500 (EST), Michael Dugger <dugger at jlab.org> 
> wrote:
>
>> 
>> Derek,
>> 
>> There is always the possibility that there is something wrong in my code. 
>> We will have to sort this out.
>> 
>> One thing you could do as a check, is see how the cascade-(1320) signal to 
>> background looks when you do a missing mass (MassX) from the reaction:
>> gamma p -> K+ K+ X
>> 
>> If we can get agreement on the cascade, we can then look for differences in 
>> the way our Omega- is dealt with.
>> 
>> It might also be useful to set the generator to real photons, generate g6 
>> energies and compare to John Price's results. There will be detector 
>> efficiency differences, but perhaps the signal to background ratios we get 
>> simulating CLAS12 will not be too very different than what Price got.
>> 
>> I'm sure we will get this figured out. This is just a normal part of the 
>> development cycle.
>> 
>> Take care,
>> Michael
>> 
>> On Fri, 24 Feb 2012, Derek Glazier wrote:
>> 
>>> Hi Mike,
>>>  My analysis of the same final state gives quite different results. 
>>> Basically I just weight the number of generated events by the cross 
>>> sections of total hadronic events (130,000nb) to Omega- (0.5nb). i.e I use 
>>> 260,000 times more generated events for the total hadronic background, 
>>> than for Omega-. I simulated 200M pythia events and get a signal to 
>>> background ratio of around 1:10. I attach the plot. I generate events 
>>> tagged by the forward tagger with e- energy range 0.5-6GeV. I do not use 
>>> any PID scheme as such, just assume the particles are identified 
>>> correctly. I also cut on the K0 mass and pi-pi+ coming from the same 
>>> vertex, but I do not care if it is detached from the K+ vertex or not.
>>>  I also attach a similar plot for also detecting the K- where the 
>>> situation is improved and in particular, if a vertex cut is used the 
>>> background is zero.
>>>  I prefer your results however, so will try and see if I can track down a 
>>> bug.
>>> Cheers
>>> Derek
>>> 
>>> 
>>> On 02/24/12 17:12, Michael Dugger wrote:
>>>> I have the cross section for the Omega- set to
>>>> (1/10)*crossSection(neutral cascade).
>>>> 
>>>> -Michael
>>>> 
>>>> On Fri, 24 Feb 2012, andrei afanasev wrote:
>>>> 
>>>>> Mike,
>>>>> The signal looks very good. What was the value you used for the 
>>>>> production cross section for Omega? Since it is unknown, it makes sense 
>>>>> to vary it within realistic estimates that we put in the Omega LOI 
>>>>> before.
>>>>> -Andrei
>>>>> -----Original Message-----
>>>>> From: Michael Dugger<dugger at jlab.org>
>>>>> Sender: clas12_verystrange-bounces at jlab.org
>>>>> Date: Fri, 24 Feb 2012 11:32:26
>>>>> To:<clas12_verystrange at jlab.org>
>>>>> Reply-To: clas12_verystrange at jlab.org
>>>>> Subject: [Clas12_verystrange] Omega-
>>>>> 
>>>>> 
>>>>> Hi,
>>>>> 
>>>>> I have generated ~100 million background events and blended them with an
>>>>> Omega- signal, and want to see if the plot I get seems reasonable.
>>>>> 
>>>>> The plot OmegaMbranch.gif is attached and shows the relative amount of
>>>>> background to be expected when a K+ K+ and K0 is seen (the K0 is
>>>>> reconstructed from a pi+ pi- pair). I have put in a PID scheme, but do 
>>>>> not
>>>>> approximate the Cerenkov counter response. The PID is only from beta and
>>>>> momentum information.
>>>>> 
>>>>> Thanks for your time.
>>>>> 
>>>>> Take care,
>>>>> Michael
>>>>> 
>>>>> _______________________________________________
>>>>> Clas12_verystrange mailing list
>>>>> Clas12_verystrange at jlab.org
>>>>> https://mailman.jlab.org/mailman/listinfo/clas12_verystrange
>>>>> 
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>>> 
>>> 
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>>> Scotland, with registration number SC005336.
>>> 
>>> 
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>
> Igor Strakovsky, SAID CNS The George Washington University
> Tel: 703-726-8344(NV),202-994-4742(FB),Skype: igors1945_2
> Fax: 202-994-3001(FB),Emails: igor at va.gwu.edu, igor at jlab.org
>