[Clas12_verystrange] Omega-

[Igor Strakovsky]

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