[Clas12_verystrange] Omega-

[Michael Dugger]

Igor,

It is good you brought up the cross section issue. It has made me think 
that I need to check that the number I quoted is correct.

Derek and my results do not agree so there is a problem somewhere. At some 
point we will converge on an answer.

Take care,
Michael

On Fri, 24 Feb 2012, Igor Strakovsky wrote:

> Sorry, Mike, for the confusing.  Let me say that 0.3 nb or 0.36 nb are the
> same at this stage of our project.  igor
>
> On Fri, 24 Feb 2012 13:46:36 -0500 (EST), Michael Dugger <dugger at jlab.org> 
> wrote:
>
>> 
>> 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
>