[Solid_ec] Fwd: Re: Questions about LHCb 1) MAPMT readout and 2) fiber connectors

[Zhiwen Zhao]

Hi, All

What Stephane mentioned the two references
One is just the LHCb detector paper
https://www.dropbox.com/s/imukuj9vw038zfr/jinst8_08_s08005.pdf
The other is maybe his thesis where the preshower readout parts are in 
English
https://www.dropbox.com/s/bj86tmjq27e5sin/HDR_SMonteil.pdf

Zhiwen

-------- Original Message --------
Subject: Re: Questions about LHCb 1) MAPMT readout and 2) fiber connectors
Date: Mon, 14 Apr 2014 09:57:16 +0200
From: Stephane Monteil <monteil at in2p3.fr>
To: Xiaochao Zheng <xiaochao at jlab.org>
CC: xavier vilasis cardona <xavier.vilasis.cardona at cern.ch>, 
Jian-ping Chen <jpchen at jlab.org>, Zhiwen Zhao <zwzhao at jlab.org>



	Dear Xiaochao,

Sorry for the late answer to your message.
I try here to answer some of your questions:

>
> Question #1: If I understand correctly, the gain of the MAPMT is controlled to 5E3 to avoid high anode current and thus aging of the PMT. At this low gain, however, I estimate that the MIP signal is at the tens of microvolts level.  I know that MAPMTs are readout by a specifically designed very-front-end electronics.  Can you tell me what is the pre-amp gain of the VFE?  Or if there is no obvious pre-amp built-in, how did you successfully identify the MIP peak from regular electronic noises?  Does the VFE have very low noise (below microvolt level)?
	
The SPD and PS gains are actually different by a typical factor 10.
The PS has the lowest gain to cope with the anticipated aging
of the tube that we have observed at lab mimicking the LHC
conditions. It is a pleasure to write that this measure was
successful :)

For the PS VFE electronics,  there is no obvious pre-amp built-in.
The integration electronics is an home-made asic. It starts with
  a low-noise current conveyer multiplying by the current by a
factor 10. Unfortunately, we have not documented the
achievements in journals but internal notes.  Please see the
following references where some information are gathered:

.) http://iopscience.iop.org/1748-0221/3/08/S08005/
.) http://tel.archives-ouvertes.fr/tel-00561855/
    [For the latter, the parts you're interested in are in english]

MIPs are beautifully seen at ~7 times the noise level.  I'm pretty
sure that there are things to gather for your study from the SPD
VFE electronics design as well.

>
> Question #2:  I have read from the note named "mechps" that the 1-1 connector used by LHCb were using the concept of the OPAL experiment. Did you make these connectors in-house?  Approximately how much does each cost?  In addition, is there any possibility that I can borrow one connector to study, so that we can make them here in-house either at UVa or JLab?


What is mechps? Which connector are you referring to?
	
	Best Regards, Stephane.

Stephane Monteil. LHCb Experiment. 
Laboratoire de Physique  Corpusculaire
Universite Blaise Pascal / in2p3-cnrs. 
                                24, Avenue des Landais
Phones : +33 4 73 40 79 17 (Lab.) 
                                  63177 Aubiere CedexF
                  +41 22 767 57 85 (Cern)







On Apr 1, 2014, at 10:52 PM, Xiaochao Zheng wrote:

> Dear Xavier and Stephane:
>
> I am an experimental nuclear physicist and I do research primarily at Jefferson Lab in Newport News, VA.  We are doing detector R&D for a JLab 12 GeV Project called "SOLID", which stands for "SOlenoid Large Intensity Device". The physics of SOLID is focused on SIDIS and Parity violation in DIS measurements.
>
> I am coordinating the electromagnetic calorimeter R&D for SOLID, which consists of a SPD, a Preshower and a Shower. The design of these three components are very similar to the calorimeter at LHCb and we found the LHCb design very helpful to our work.
>
> I am some specific questions about the MAPMT readout for the SPD/PS.
>
> Question #1: If I understand correctly, the gain of the MAPMT is controlled to 5E3 to avoid high anode current and thus aging of the PMT. At this low gain, however, I estimate that the MIP signal is at the tens of microvolts level.  I know that MAPMTs are readout by a specifically designed very-front-end electronics.  Can you tell me what is the pre-amp gain of the VFE?  Or if there is no obvious pre-amp built-in, how did you successfully identify the MIP peak from regular electronic noises?  Does the VFE have very low noise (below microvolt level)?
>
> Question #2:  I have read from the note named "mechps" that the 1-1 connector used by LHCb were using the concept of the OPAL experiment. Did you make these connectors in-house?  Approximately how much does each cost?  In addition, is there any possibility that I can borrow one connector to study, so that we can make them here in-house either at UVa or JLab?
>
> The same applies to the 100-100 fiber connector. Can you lend us a sample?
>
> Please don't be surprised if you hear your LHCb collaborators received similar questions from me.  I have sent emails to Dr. Perret at in2p3, but he is probably too busy to answer this type of specific questions.  I am also copying this to our SOLID program manager, Jianping Chen from Jefferson Lab.
>
> thanks and I look forward to hearing from you.
>
> Best regards,
>
> Xiaochao
> ----------------------------------------------------------------------------
> Associate Professor, Department of Physics, University of Virginia
> 382 McCormick Rd, Charlottesville, VA 22904
> Telephone: (434) 243-4032 (during academic year); or (757) 810-2885 (summer)
> Homepage: http://people.virginia.edu/~xz5y/Main.html
> ----------------------------------------------------------------------------
>