[Halld-tagger] specs for microscope readout power supplies
Fernando J Barbosa
barbosa at jlab.org
Mon Dec 9 10:56:29 EST 2013
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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