[Halld] Proposed intensity scan for Fall 2018

Mon Nov 19 13:58:55 EST 2018

Probably would be best to prescale the main trigger, at least, otherwise we
could waste time fiddling with the DAQ.
-Richard

On Mon, Nov 19, 2018 at 1:56 PM Richard Jones <rjones30 at gmail.com> wrote:

> On Mon, Nov 19, 2018 at 1:51 PM Eugene Chudakov <gen at jlab.org> wrote:
>
>> Let me remind you that with the currently used DAQ software we would
>> be limited to about 1GB/s, or about 400nA without prescaling (or somewhat
>> lower for reliable operations).
>>
>> The front-end limit would be about 80kHz, or also 400nA.
>>
>> We may try to use a new DAQ software (the Sergey's version), which can go
>> to >2GB/s. The front-end limits would still apply.
>>
>> Eugene
>>
>> On Mon, 19 Nov 2018, Sean Dobbs wrote:
>>
>> > Hi Justin,
>> >
>> > If the high intensity points are cheap, maybe it would be useful to
>> have a finer grained scan, just in case we find something that we need to
>> investigate in more detail?  Say, adding 400 and 600 nA points?
>> >
>> > Cheers,
>> > Sean
>> >
>> > On Mon, Nov 19, 2018 at 11:56 AM Justin Stevens <jrsteven at jlab.org
>> <mailto:jrsteven at jlab.org>> wrote:
>> > Hi Richard,
>> >
>> > Thanks for your feedback.  See below ->
>> >
>> > On Nov 19, 2018, at 11:34 AM, Richard Jones <richard.t.jones at uconn.edu
>> <mailto:richard.t.jones at uconn.edu>> wrote:
>> >
>> > Hello Justin,
>> >
>> > If we want to understand rate-related systematics, wouldn't it be
>> better to push the upper limit of the scan higher? This way we learn
>> something about what starts to go wrong at lower intensities, where we
>> might want to run during the high-intensity period.
>> >
>> > If it doesn't break anything, we should take some data at higher
>> intensities, even if we have to prescale the trigger. I propose running two
>> or three more points up to 700 nA on this diamond. This 700uA comes from
>> the original design intensity for GlueX which was 1e8 photons per second on
>> the target in the range 8.4 - 9.0 GeV (or 8.2 - 8.8 GeV with the present
>> endpoint).
>> >
>> > Sure, high intensity points are “cheap”, so this puts us at ~30 hours
>> at 100% efficiency.  I added these points to the scan, if we’re comfortable
>> going to this high an intensity (from a detector safety and trigger point
>> of view).
>> >
>> > I realize that this 5e-4 radlen in the spreadsheet for this diamond is
>> just a placeholder, but that value should be closer to 3e-4. Radiation
>> length is not really a valid metric for a coherent bremsstrahlung spectrum,
>> but in the low-energy tail it is valid, where the radiation length of
>> diamond is close to 15um as long as you stay away from the channeling
>> condition. To get this, you cannot just take amorphous carbon and rescale
>> it by the density, of course, as the crystal structure modifies the
>> radiation length at all orientations.
>> >
>> > I agree the diamond radiation length is a bit of a fudge, but it
>> actually cancels in my calculation of the expected run time.  The only
>> thing I use is the total trigger rate for the nominal intensity (~45 kHz
>> for diamond) and scale by the current to get the time required.
>> >
>> > -Justin
>> >
>> >
>> > -Richard
>> >
>> > On Mon, Nov 19, 2018 at 10:11 AM Justin Stevens <jrsteven at jlab.org
>> <mailto:jrsteven at jlab.org>> wrote:
>> > Dear Collaborators,
>> >
>> > Following the discussion at this morning’s RC meeting for an intensity
>> scan this Fall, here is what I would propose:
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__na01.safelinks.protection.outlook.com_-3Furl-3Dhttps-253A-252F-252Furldefense.proofpoint.com-252Fv2-252Furl-253Fu-253Dhttps-2D3A-5F-5Fdocs.google.com-5Fspreadsheets-5Fd-5F1UT3o4yJ-2D2DavlIQzmZKJo2nRrgVPzYKJvGPJ0oqAn81Oo-5Fedit-2D3Fusp-2D3Dsharing-2526d-253DDwIGaQ-2526c-253Dlz9TcOasaINaaC3U7FbMev2lsutwpI4-2D-2D09aP8Lu18s-2526r-253DMwj7jqW-5FGg8VvugDHdwA5w-2526m-253D-5FX3Z46cZYdB3Mq0066MeIIqspYRtV5uWmIdE3DKDD9E-2526s-253D27qXEoJLy9v6wZ7LpbadD07mVXM1aWPiEZiTuLYtHlE-2526e-26amp-3Bdata-3D02-257C01-257Crichard.t.jones-2540uconn.edu-257Cfb0599295e7f467e6fbc08d64e4ffcef-257C17f1a87e2a254eaab9df9d439034b080-257C0-257C0-257C636782502793219428-26amp-3Bsdata-3DXAShNOwPv7CBj7HipP-252FBZ-252Fea9oXBpNLvKCXJvyz-252Be1Y-253D-26amp-3Breserved-3D0-3D&d=DwIFaQ&c=lz9TcOasaINaaC3U7FbMev2lsutwpI4--09aP8Lu18s&r=Mwj7jqW_Gg8VvugDHdwA5w&m=vrEVBBS56r6QE4_7koIGu5N7-140pDK1dHieGuAr2Xo&s=PFPM-xcEnc6Dm0X0QpEPANL4YkPx12r8XQ01qpqMGGU&e= 
>> <
>> https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Furldefense.proofpoint.com%2Fv2%2Furl%3Fu%3Dhttps-3A__na01.safelinks.protection.outlook.com_-3Furl-3Dhttps-253A-252F-252Fdocs.google.com-252Fspreadsheets-252Fd-252F1UT3o4yJ-2DavlIQzmZKJo2nRrgVPzYKJvGPJ0oqAn81Oo-252Fedit-253Fusp-253Dsharing-26data-3D02-257C01-257Crichard.t.jones-2540uconn.edu-257C2a054bc8dc824538f06908d64e314804-257C17f1a87e2a254eaab9df9d439034b080-257C0-257C0-257C636782370905211494-26sdata-3D9Sov7Fn68-252F0EsSrmdAiZ-252BHwwCC8KslfwMZPmqOufmqM-253D-26reserved-3D0%26d%3DDwMFaQ%26c%3Dlz9TcOasaINaaC3U7FbMev2lsutwpI4--09aP8Lu18s%26r%3DcIyw2PFFtpuc0ZvlKFxF6UnQ9C9dChESxxwL_XrGKB8%26m%3D5x60TVJ8MWSM9A2jrjY1xKIskHZbATEXmLaQNxYDIk0%26s%3DVNrl0oRFsfR28nvFv8Oyp7omkfKi-EFVp6gylZAv0yI%26e&data=02%7C01%7Crichard.t.jones%40uconn.edu%7Cfb0599295e7f467e6fbc08d64e4ffcef%7C17f1a87e2a254eaab9df9d439034b080%7C0%7C0%7C636782502793219428&sdata=lr8hqjS7ue8zE4G6nwejZXi5KSwLwp28%2F7xxhMTaWdA%3D&reserved=0=>.
>> There are two sheets at this link: RunPeriod-2018-08 (the proposal for this
>> week) and RunPeriod-2018-01 (the data we've collected previously).  As a
>> reminder, in Spring 2018 we did not have any high-statistics intensity scan
>> with the final Tungsten foil installed in the beamline.
>> >
>> > The proposal covers the same range of intensity (Beam current x RL) as
>> we had in Spring 2018, with 100M events at each setting (aside from the
>> very low intensity, where the rate is too low).  As Sergey requested, this
>> also includes a raw mode run at each setting of 1M events, assumed to run
>> at ~3 kHz.  The goal is to have a complete set of intensity scan data for
>> efficiency studies with this Fall 2018 data.
>> >
>> > The estimated beam time required for this proposal is ~28 hours at 100%
>> efficiency, so it would likely take at least 2 days of calendar time to
>> complete.
>> >
>> > Comments/suggestions welcome,
>> > Justin
>> > _______________________________________________
>> > Halld mailing list
>> > Halld at jlab.org<mailto:Halld at jlab.org>
>> >
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>> <
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>> >
>> > _______________________________________________
>> > Halld mailing list
>> > Halld at jlab.org<mailto:Halld at jlab.org>
>> >
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>>
>
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