The Braidwood reactors are of the pressurized water type. The core of each reactor
is a verical cylinder the measures 3.65 m high, and 3.37 m in diameter. A usefule source of
information regarding reactors around the world is the International Nuclear Safety Center
webpage:
http://www.insc.anl.gov/pwrmaps/
The source isn't necessarily uniform over the volume of the cylinder. Operatations control the
power output by adjusting the control rods. The far detector may not see any of these effects
to a level of precision required by the experiment, but the near detector may. When we compare
the rate of the far detectors to the near detector, the geometry of the source will somehow need
to be taken into account. I don't know if this is a serious systematic.
Ray Stefanski
Fermilab, MS122
P.O. Box 500
Batavia, Il 60510
Phone: 630.8403872
----- Original Message -----
From: Jonathan Link <link@fnal.gov>
Date: Sunday, December 26, 2004 10:12 pm
Subject: Re: coordinate system
> Hi All,
>
> I think that Josh is right. The inverse beta decay events have
> almost
> no intrinsic directional correlation (see the Vogal and Beacom
> paper on
> inverse beta decay) and the isotropic scintillation light will
> likely
> mask the minor correlations that are present. That means that the
> most
> relevant coordinate system is the one that is azimuthally
> symmetric
> about the neck of the detector. Nevertheless, Dick makes the good
> point
> that coordinate transformations are to perform.
>
> Also, I believe that we will want to reconstruct events in a local
> coordinate system with the origin at the center of the detector.
> We
> will likely employ a global system, with the origin at the
> midpoint
> between the two reactors, only in the final analysis.
>
> -Jon
>
> Richard K. Yamamoto wrote:
>
> >Hi Josh,
> >
> > Thanks for the heads-up on the vertical. However,
> transforming from
> >the "beam" coordinates to the natural "vertical" coordinates is
> simply a
> >single rotation around the horizontal axis by different fixed
> angles for
> >the two detector systems, such that the vertical axes for the
> "beam" and
> >"vertical" systems coincide. Thus, it is easy to transform
> coordinates
> >from one system to the other, if needed.
> >
> >Best regards,
> >Dick
> >
> > +----------------------------------------------------------------
> ------+
> >
> >On Sat, 25 Dec 2004, Josh R Klein wrote:
> >
> >
> >
> >>Hi, Dick,
> >>
> >>
> >>> I don't think this is
> >>>important since the vertical direction may be a symmetry axis
> for the veto
> >>>but is of no special interest for the detectors, whereas the
> beam
> >>>directions are.
> >>>
> >>>
> >> Actually, vertical is more important for the detector symmetry than
> >>is the `beam' direction. The neck of the vessel, the
> calibration system's
> >>primary axis, and the support structure for the vessel all
> create cylindrical
> >>rather than spherical symmetry, with the z-axis of the cylinder
> being>>the detector's vertical. Given this, using z as upward
> works best for
> >>both the veto and the detector.
> >>
> >> Thanks,
> >> Josh
> >>
> >>
> >>
> >>The veto could do everything in earth vertical
> >>
> >>
> >>>coordinates and transform results into detector coordinates.
> Since the
> >>>two detectors are completely independent from each other, and
> ultimately
> >>>we are interested in flux direction from reactors to detectors,
> having two
> >>>coordinate systems seem to be a minor inconvenience, if any.
> >>> I'd appreciate any comments on this suggestion.
> >>>
> >>>Best regards,
> >>>Dick
> >>> +--------------------------------------------------------------
> --------+
> >>>
> >>>On Thu, 23 Dec 2004, Maury Goodman wrote:
> >>>
> >>>
> >>>
> >>>>The neutrinos are isotropic, but there is a geometry effect
> (I'm not
> >>>>sure if this is
> >>>>what Dick was referring to or not.) The core has a finite
> size, and
> >>>>because fuel rods are
> >>>>loaded to maximize power, the energy distribution of the
> neutrino source
> >>>>varies through the core.
> >>>>There is a small angular effect on the neutron in inverse beta
> decay.
> >>>>Applied together, there is
> >>>>a small effect on the near detector, and effectively none at
> the far
> >>>>detector. I have a memory that
> >>>>someone calculated this as a 0.1% difference, but I couldn't
> find it
> >>>>this afternoon. It can obviously
> >>>>be calculated with a good Monte Carlo, and then minimized
> further with
> >>>>some information about fuel
> >>>>loading, if needed.
> >>>>Maury
> >>>>
> >>>>"Bolton, Tim" wrote:
> >>>>
> >>>>
> >>>>>Dick,
> >>>>>
> >>>>>I think the answer is that isotropy is assumed and highly
> likely. But I suspect that this has never been verified with the
> antineutrinos, although perhaps it has with the beta decay electrons.
> >>>>>
> >>>>>The immediate issue with the coordinate system is to define
> the veto system in simulation in a way that the nu detector
> simulation understand it and vice versa. But it's probably worth
> thinking about making a good overall choice.
> >>>>>
> >>>>>Happy Holidays
> >>>>>
> >>>>>TB
> >>>>>
> >>>>>Tim Bolton
> >>>>>Professor
> >>>>>High Energy Physics Group
> >>>>>Kansas State University
> >>>>>tbolton@ksu.edu
> >>>>>785-532-1664
> >>>>>
> >>>>>________________________________
> >>>>>
> >>>>>From: Richard K. Yamamoto [rky@mit.edu]
> >>>>>Sent: Thu 12/23/2004 1:42 PM
> >>>>>To: stefanski@fnal.gov
> >>>>>Cc: Bolton, Tim; Jonathan Link; braidwood@hep.uchicago.edu
> >>>>>Subject: Re: RE: coordinate system
> >>>>>
> >>>>>Hi Folks,
> >>>>>
> >>>>> I'd like to add my two cents, which is all what I say
> may be worth.
> >>>>> The details of coordinate systems, etc. seems to me
> somewhat minor,
> >>>>>since once defined, its just a matter of coordinate
> transformations,>>>>>regardless of how complicated this may end up
> being. I have a naive
> >>>>>question, not quite related to coordinates but may be a
> bigger sytematic
> >>>>>question: how well do we know the neutrino flux distribution
> in angle with
> >>>>>respect to, say, the surface of the ground? Since the
> detectors are at
> >>>>>different distances from the reactor core, if this
> distribution is not
> >>>>>known because it may not be isotropic, the relative flux
> between detectors
> >>>>>may not be able to be calculated to the precision we need.
> Perhaps this
> >>>>>can be studied through simulations, but can we ever measure this?
> >>>>> I'd be happy if someone can tell me I'm worrying about
> nothing, so I
> >>>>>can enjoy the Holidays.
> >>>>>
> >>>>>Best regards, and Happy Holidays!
> >>>>>Dick Yamamoto
> >>>>>
> >>>>> +------------------------------------------------------------
> ----------+
> >>>>>
> >>>>>On Wed, 22 Dec 2004 stefanski@fnal.gov wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>>>>Hi,
> >>>>>>
> >>>>>>1. If "up" is determined by the liquid, each detector will
> have a slightly different vertical axis. The earth's curvature is
> about 6 micro-radians per mile. Small, but might be significant
> for the difference between near and far detector.
> >>>>>>
> >>>>>>2. The reactor core may not be known precisely. Has anyone
> written a realistic model for the source? How do we define the
> "center of the core."
> >>>>>>
> >>>>>>3. If we can define the core centers and draw a line between
> them, we would like to know the axis of symmetry, which would
> presumably be perpendicular to this line. The axis of symmetry
> could be defined as the intersection of the vertical and
> horizontal planes of symmetry, if they exist. Because we are
> dealing with extended sources, the vertical and horizontal planes
> of symmetry might not the orthoginal to each other.
> >>>>>>
> >>>>>>These will be small effects, but we should probably keep
> them in mind as we go along. I'm especially interested in knowing
> a bit more about the size and distribution of the reactor core.
> >>>>>>
> >>>>>>Cheers,
> >>>>>>
> >>>>>>Ray Stefanski
> >>>>>>Fermilab, MS122
> >>>>>>P.O. Box 500
> >>>>>>Batavia, Il 60510
> >>>>>>Phone: 630.8403872
> >>>>>>
> >>>>>>----- Original Message -----
> >>>>>>From: "Bolton, Tim" <bolton@phys.ksu.edu>
> >>>>>>Date: Wednesday, December 22, 2004 8:16 am
> >>>>>>Subject: RE: coordinate system
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>>Precisely. After talking with Glenn and Josh and looking
> at what
> >>>>>>>KAMLAND and SNO did, I think a more
> >>>>>>>sensible choice might be:
> >>>>>>>
> >>>>>>>z-axis -- plumb-line up, or zenith angle 0. Our liquid
> always>>>>>>>measures this.
> >>>>>>>
> >>>>>>>xy-plane is perpindicular to z.
> >>>>>>>
> >>>>>>>x-axis (phi=0) -- draw a line from the midpoint of the two
> >>>>>>>reactor cores to the center of the upstream near detector (if
> >>>>>>>there are two, then to the one most likely to be fixed.
> Project>>>>>>>the line to the xy-plane.
> >>>>>>>
> >>>>>>>
> >>>>>>>y = z X x.
> >>>>>>>
> >>>>>>>This way the z-axis is the one about which the detector has
> >>>>>>>rotational symmetry. The beam is mostly along the x axis
> with a
> >>>>>>>small -z component and a y component that typically
> averages to
> >>>>>>>zero. The x and y axes will also be approximate symmetry
> axes for
> >>>>>>>the cavern and veto structures.
> >>>>>>>
> >>>>>>>TB
> >>>>>>>
> >>>>>>>
> >>>>>>>Tim Bolton
> >>>>>>>Professor
> >>>>>>>High Energy Physics Group
> >>>>>>>Kansas State University
> >>>>>>>tbolton@ksu.edu
> >>>>>>>785-532-1664
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>-----Original Message-----
> >>>>>>>From: Jonathan Link [link@fnal.gov]
> >>>>>>>Sent: Tue 12/21/2004 10:52 PM
> >>>>>>>To: Bolton, Tim
> >>>>>>>Cc: reactor-vwg@mit.edu
> >>>>>>>Subject: Re: coordinate system
> >>>>>>>
> >>>>>>>Which beam? Reactor one or reactor two?
> >>>>>>>
> >>>>>>>Bolton, Tim wrote:
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>>I'm not sure we have even made a basic convention for the
> >>>>>>>>
> >>>>>>>>
> >>>>>>>coordinate system.
> >>>>>>>
> >>>>>>>
> >>>>>>>>ReactorFsim tacitly assumes
> >>>>>>>>
> >>>>>>>>z = "beam direction", with z increasing as one moves away from
> >>>>>>>>
> >>>>>>>>
> >>>>>>>reactor.
> >>>>>>>
> >>>>>>>
> >>>>>>>>y = "up"
> >>>>>>>>
> >>>>>>>>x = y X z
> >>>>>>>>
> >>>>>>>>And x and y don't really matter.
> >>>>>>>>
> >>>>>>>>But there are subtleties.
> >>>>>>>>
> >>>>>>>>-- Where is x=y=z=0? Center of one detector (which one).
> >>>>>>>>
> >>>>>>>>
> >>>>>>>Midpoint between two reactor cores? Ed's office?
> >>>>>>>
> >>>>>>>
> >>>>>>>>-- Can we assume that all detectors are centered on the z-
> axis.>>>>>>>>
> >>>>>>>>-- y is not really "up" in this convention, because of "beam
> >>>>>>>>
> >>>>>>>>
> >>>>>>>tilt". Should it be "up" as in vertical or "up as
> perpindicular>>>>>>>to beam?
> >>>>>>>
> >>>>>>>
> >>>>>>>>Maybe there is a better choice. We should make it before we
> >>>>>>>>
> >>>>>>>>
> >>>>>>>start introducing elements that define direction.
> >>>>>>>
> >>>>>>>
> >>>>>>>>TB
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>Tim Bolton
> >>>>>>>>Professor
> >>>>>>>>High Energy Physics Group
> >>>>>>>>Kansas State University
> >>>>>>>>tbolton@ksu.edu
> >>>>>>>>785-532-1664
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>-----Original Message-----
> >>>>>>>>From: ELog@CYCLOTRON.mit.edu [ELog@CYCLOTRON.mit.edu]
> >>>>>>>>Sent: Tue 12/21/2004 9:26 AM
> >>>>>>>>To: reactor-vwg@MIT.EDU
> >>>>>>>>Subject: New ELOG entry
> >>>>>>>>
> >>>>>>>>A new entry has been submitted on cyclo.mit.edu
> >>>>>>>>
> >>>>>>>>Logbook : Veto Working Group
> >>>>>>>>Author : Peter Fisher
> >>>>>>>>Type : Agenda
> >>>>>>>>Category : General
> >>>>>>>>Subject : Short phone meeting Tuesday, 3:30
> pm, 617-
> >>>>>>>>
> >>>>>>>>
> >>>>>>>324-7520
> >>>>>>>
> >>>>>>>
> >>>>>>>>Logbook URL :
> http://cyclo.mit.edu:8080/Veto+Working+Group/6>>>>>>>>
> >>>>>>>>=================================
> >>>>>>>>
> >>>>>>>>Please note the meeting will start a half hour later than
> usual.>>>>>>>>
> >>>>>>>>Agenda
> >>>>>>>>------
> >>>>>>>>
> >>>>>>>>1. Nomenclature and general veto configurations - 10'
> >>>>>>>> At the last meeting with discussed some general
> configurations>>>>>>>>
> >>>>>>>>
> >>>>>>>for the
> >>>>>>>
> >>>>>>>
> >>>>>>>>veto simulation. I've made some simple sketches which are
> on the
> >>>>>>>>
> >>>>>>>>
> >>>>>>>E-log.
> >>>>>>>
> >>>>>>>
> >>>>>>>>I'm happy to change any label to be consistant with
> history, but
> >>>>>>>>
> >>>>>>>>
> >>>>>>>we should
> >>>>>>>
> >>>>>>>
> >>>>>>>>agree on what we call things.
> >>>>>>>>
> >>>>>>>>2. Simulation progress and plans - 15'
> >>>>>>>> Work has begun on flux functions for ReactorFsim and
> ther are
> >>>>>>>>opprotunities for people to contribute. We should briefly
> review>>>>>>>>
> >>>>>>>>
> >>>>>>>what is
> >>>>>>>
> >>>>>>>
> >>>>>>>>being done.
> >>>>>>>>
> >>>>>>>>The next meeting will be Jan. 4, 2004.
> >>>>>>>>
> >>>>>>>>Peter
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >>>>>>>
> >
> >
> >
>
>
Received on Mon Dec 27 11:03:10 2004