[Halld-tagger] specs for microscope readout power supplies
Alexander Somov
somov at jlab.org
Mon Dec 9 11:20:16 EST 2013
Hi Fernando,
I've been completely distracted with the fcal trigger/daq setup
and the PS fabrication/testing. The most convenient time for
doing this electromagnetic bg simulation would be the Christmas break.
I think that the em background origination from the radiator
would not be difficult to shield by placing some blocks
(but i certainly can estimate it contribution).
Cheers,
Alex
P.S. The MPOD solution for the microscope seems to be the best
as we can use the same control for several sub-detectors
it is no the cheapest one... but still not that expensive)
On Mon, 9 Dec 2013, Fernando J Barbosa wrote:
> Hi Alex,
>
> A few weeks ago, Eugene mentioned that you were going to perform additional
> simulations about the radiation levels in the tagger hall so we could settle
> on the racks placement. Did you have a chance to look into this?
>
> Thanks and best regards,
> Fernando
>
>
> On 12/9/2013 10:56 AM, Fernando J Barbosa wrote:
>> Hi Hovanes,
>>
>> My plan is to use a mini MPOD with two modules, one is the familiar 8V and
>> the other is a 120V. Both are Wiener MPODs and I can segment into 6 TAGM
>> backplane feeds. So, the controls are the same as the rest of the Hall D
>> MPODs. This solution will cost less than $15k. I will distribute the plan
>> shortly.
>>
>> Best regards,
>> Fernando
>>
>>
>> On 12/9/2013 10:51 AM, Hovanes Egiyan wrote:
>>> Hi Richard,
>>> what type of controls is needed for these? Do we need to be able to
>>> remotely
>>> control them, turn them on/off, power cycle them?
>>> Hovanes.
>>>
>>> On 12/09/2013 10:37 AM, Fernando J Barbosa wrote:
>>>> Hi Richard,
>>>>
>>>> OK, looks good. I will look at options for the supplies.
>>>>
>>>> Thanks and best regards,
>>>> Fernando
>>>>
>>>> On 12/9/2013 10:28 AM, Richard Jones wrote:
>>>>> Fernando,
>>>>>
>>>>> Our background study showed that we could continue to function for 10
>>>>> years of high-rate running without annealing, just allowing the dark
>>>>> rate to increase at the rate that was measured in Hall B and allowing
>>>>> the supply current to increase. Under the zero-shielding scenario, just
>>>>> leaving the electronics unshielded in the tagger hall, we estimated that
>>>>> we would reach the point where we would need to do something (eg. anneal
>>>>> or replace the SiPM's) after 10 years of high-rate running. The usual
>>>>> assumptions were applied (100 days of running per year, standard 20
>>>>> micron diamond, 12 GeV electrons at 2.2 microAmps). With shielding, we
>>>>> expect to reduce this figure by a factor of 5-10 (the simulation gave a
>>>>> factor around 8), so we should be able to run for the duration of GlueX
>>>>> without annealing.
>>>>>
>>>>> I agree with you that we can segment the supplies. Each of them can be
>>>>> split up to 6 ways, because there are 6 identical backplanes in the
>>>>> system. The specs we posted were for the total sum of all 6 backplanes.
>>>>>
>>>>> -Richard J.
>>>>>
>>>>>
>>>>> On Mon, Dec 9, 2013 at 9:52 AM, Fernando J Barbosa <barbosa at jlab.org
>>>>> <mailto:barbosa at jlab.org>> wrote:
>>>>>
>>>>> Hi Richard,
>>>>>
>>>>> Certainly the rates in the tagger are higher but what is your
>>>>> planning for annealing the SiPMs? I am just curious given the
>>>>> higher rates.
>>>>>
>>>>> Regarding the power supplies, you mentioned the possibility of
>>>>> having three supplies instead of one for the whole system. Is
>>>>> it possible to consider further segmentation? One channel per
>>>>> backplane? Do you have a document that shows the whole system
>>>>> as installed? The issue is also related to the space available
>>>>> under the magnet.
>>>>>
>>>>> Best regards,
>>>>> Fernando
>>>>>
>>>>>
>>>>>
>>>>> On 12/6/2013 10:09 AM, Richard Jones wrote:
>>>>>> Fernando,
>>>>>>
>>>>>> These estimates for the BCal do not apply to the TAGM, where
>>>>>> the rates are much higher. We can set up a meeting to discuss
>>>>>> this further if you feel we need it. We worked out these
>>>>>> rates back during the design phase for the readout
>>>>>> electronics, and had them reviewed within the photon beam
>>>>>> working group. Also keep in mind that the neutron flux is much
>>>>>> higher in the tagger hall than in the experimental hall. On
>>>>>> the other hand, the TAGM can operate efficiently at much
>>>>>> higher single-pixel rates than can a calorimeter because it is
>>>>>> not producing an energy measurement, but only time, and the
>>>>>> photon statistics are high, <n> = 350-400 within a 15ns
>>>>>> window. We are shielding these electronics, but we only
>>>>>> expect to cut down the neutron flux by about a factor 10-20 in
>>>>>> this way. Alex Somov did the neutron rates and shielding
>>>>>> studies for us, and can provide more details in this regard.
>>>>>>
>>>>>> -Richard J.
>>>>>>
>>>>>>
>>>>>> On Fri, Dec 6, 2013 at 9:04 AM, Fernando J Barbosa
>>>>>> <barbosa at jlab.org <mailto:barbosa at jlab.org>> wrote:
>>>>>>
>>>>>> Hi Richard,
>>>>>>
>>>>>> In reference to the BCAL and taking Yi's measurements in
>>>>>> Hall A regarding radiation damage, we settled on a maximum
>>>>>> of 10mA for 10 arrays or 160 cells (3mm x 3mm). This works
>>>>>> out to 62.5uA per cell and your estimate is higher by a
>>>>>> factor greater than 10. What is your plan for annealing
>>>>>> the SiPMs? Frequency?
>>>>>>
>>>>>> Did you look into any supplies that might fit your
>>>>>> requirements? I recall that each backplane of the TAGM has
>>>>>> a single bias supply input, correct? This would be
>>>>>> important in considering a multi-channel supply system.
>>>>>> Please send me your latest drawings on the TAGM system and
>>>>>> its installation in the Tagger hall.
>>>>>>
>>>>>> Best regards,
>>>>>> Fernando
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 12/5/2013 10:50 PM, Richard Jones wrote:
>>>>>>> Hello Fernando,
>>>>>>>
>>>>>>> I am spec'ing the Vbias supply capacity at 500mA to allow
>>>>>>> for the maximum SiPM draw current that is permitted by
>>>>>>> the bias voltage supply system. Initially we expect the
>>>>>>> average current to be around 15 mA at full intensity (2.2
>>>>>>> uA electrons on 20 micron diamond) but that it will
>>>>>>> increase gradually over time due to radiation damage. To
>>>>>>> get the maximum current spec, I imagine the worst
>>>>>>> possible circumstances under which the radiation damage
>>>>>>> might accumulate faster than expected, and ask how much
>>>>>>> current could we sustain across all channels before the
>>>>>>> resolution and efficiency degrade significantly due to
>>>>>>> dark current. The answer to that is approximately 800uA
>>>>>>> per channel, which totals about 400mA from the supply. I
>>>>>>> rounded that up to 500mA.
>>>>>>>
>>>>>>> -Richard Jones
>>>>>>>
>>>>>>>
>>>>>>> On Thu, Dec 5, 2013 at 4:51 PM, Fernando J Barbosa
>>>>>>> <barbosa at jlab.org <mailto:barbosa at jlab.org>> wrote:
>>>>>>>
>>>>>>> Hi Richard,
>>>>>>>
>>>>>>> I looked at the specs and the bias supply current
>>>>>>> seems to be excessive at 500mA. What's the reason for
>>>>>>> this?
>>>>>>>
>>>>>>> Best regards,
>>>>>>> Fernando
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> On 12/5/2013 3:33 PM, Richard Jones wrote:
>>>>>>>
>>>>>>> Hello Alex,
>>>>>>>
>>>>>>> Here is a draft of the specs for the microscope
>>>>>>> readout dc power supplies. They can be a single
>>>>>>> unit for each of 3 levels, or a few
>>>>>>> lower-capacity supplies in tandem with the same
>>>>>>> total output capacity. Please request
>>>>>>> justification for any of the specs. One thing we
>>>>>>> do not spec here, but think would be useful, is
>>>>>>> separate delivery and sense terminals for each
>>>>>>> output. We have separate pins on the backplane
>>>>>>> connector for this purpose.
>>>>>>>
>>>>>>> http://zeus.phys.uconn.edu/wiki/index.php/Microscope_Electronics#Power_Supply_Requirements
>>>>>>>
>>>>>>> -Richard Jones
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
>>>>>
>>>>>
>>>>
>>>>
>>>>
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