From: Alberto Fasso' <fasso_at_SLAC.Stanford.EDU>

Date: Thu, 24 Jun 2010 04:22:07 -0700 (PDT)

Date: Thu, 24 Jun 2010 04:22:07 -0700 (PDT)

t>

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Dear Antonello,

please keep the correspondence on the discussion list, don't send your

questions to me alone. I am forwarding your question with my answer to th=

e list.

My answer:

How can I tell you to describe the planes, if you don't provide the neces=

sary

information???

I told you that you need to input THE COORDINATES OF A POINT and the comp=

onents

of a vector. You have given no information about a point, and an angle wh=

ich

describes the inclination of the planes: with respect to which axis?

Anyway, assuming the axis is z, you will need to input:

0.7071067811865475 -0.7071067811865475 0.0 xxx yyy zzz

where xxx yyy zzz are the coordinates of a point on the plane

and 0.707.... are respectively sin(45) and cos(45)

Be careful, in the case of a 45 degree plane the sine and cosine of the v=

ector

are also those of 45 degrees, but if the angle is different, you will nee=

d

to figure out the direction of the vector PERPENDICULAR to the plane.

This is just elementary trigonometry, nothing to do with FLUKA!

You can also choose the opposite vector:

-0.7071067811865475 0.7071067811865475 0.0 xxx yyy zzz

but then you need to change the + and - in the definition of the region.

Alberto

On Wed, 23 Jun 2010, Antonello Carloni wrote:

*> Dear alberto,
*

*> the ARB in my geometry corresponds to a figure made out of two plane
*

*> parallel to the coordinate axes and two planes which are at 45=B0 conn=
*

ecting

*> the previous ones.
*

*> Of course there is a top and a bottom plane.
*

*> My question is: how to describe the planes that are at 45 in respct to=
*

the

*> coordinate axes!?
*

*> Thank you!
*

*>
*

*>
*

*>
*

*> On Mon, 21 Jun 2010, Antonello Carloni wrote:
*

*>>
*

*>>> Dear ALL,
*

*>>> hallo again,
*

*>>> I am experiencing trouble with the implementation of the objects drw=
*

an

*>>> an=3D
*

*>>> d
*

*>>> coloured in blac in the picture attache.
*

*>>> They are what in the old Fulka were called"ARBS".
*

*>>> But when using the ARB card Fluka does not draw them,
*

*>>
*

*>> If you have followed the discussion I had on this discussion list wit=
*

h Joe

*>> Confort:
*

*>> http://www.fluka.org/web_archive/earchive/new-fluka-discuss/2998.html=
*

*>> and following,
*

*>> you will know that I have strongly recommended to never use ARBs.
*

*>> On the other hand, Joe has attached some drawings where ARBs were dra=
*

wn,

*>> although there was a geometry error.
*

*>>
*

*>>> So i decide to use Cards like PLA and XYP and YZP.
*

*>>
*

*>> Good!
*

*>>
*

*>>> No problems about the latter two ones but what about the definition =
*

of

*>>> PL=3D
*

*>>> A!?
*

*>>> The manual just says:
*

*>>>
*

*>>> * 11. Generic infinite half-space. Code: PLA Each PLA is defined by=
*

6

*>>> numbers: H_x, H_y, H_z (x, y and z components of a vector of arbitra=
*

ry

*>>> length perpendicular to the plane), V_x, V_y, V_z (coordinates of an=
*

y

*>>> point lying on the plane). The half-space "inside the body" is that =
*

from

*>>> which the vector is pointing (i.e., the vector points =3DF6utside").=
*

A PLA

*>>> definition extends over a single card in default fixed format, and o=
*

ver

*>>> two cards in high-accuracy body fixed format.
*

*>> .........
*

*>>> And so what do those vectors Hx Hy Hz when describing the plane?!
*

*>>
*

*>> Those are not "vectors", but the components of ONE vector (i.e. the
*

*>> projections
*

*>> of a vector on the 3 coordinate axes.
*

*>> One point and one vector define a generic plane without any ambiguity=
*

=2E

*>> Notice that the magnitude, or length, of the vector is irrelevant. In=
*

*>> general
*

*>> I use a unit vector, so the H_x, H_y, H_z are just its direction cosi=
*

nes.

*>> You can choose the direction of the vector as you like, but then you =
*

must

*>> take it into account when you use the plane to "build" regions (you m=
*

ust

*>> decide which part of space you prefer to be "inside" the plane, and w=
*

hich

*>> "outside").
*

*>>
*

*>>> For example , how to describe the 45=3DB0 XY Plane such as the A or =
*

B in

*>>> the
*

*>>> picture attached to this e mail!?
*

*>>> Sorry to bother you all, i might be not so clever but the interpreta=
*

tion

*>>> is really arb ,-)
*

*>>> Thank you!
*

*>>
*

*>> I am sorry, your attachment was unreadable on my mailing system. But =
*

the

*>> manual is extremely clear. You need to input 6 numbers: 3 coordinates=
*

of

*>> a point on the plane (any point, provided it is on the plane!) and 3
*

*>> components
*

*>> of a vector perpendicular to the plane (any vector, provided it is
*

*>> perpendicular to the plane!) What is "arb" in all this?
*

*>>
*

*>> Kind regards,
*

*>>
*

*>> Alberto
*

*>>
*

*>
*

*>
*

*>
*

--=20

Alberto Fasso`

SLAC-RP, MS 48, 2575 Sand Hill Road, Menlo Park CA 94025

Phone: (1 650) 926 4762 Fax: (1 650) 926 3569

fasso_at_slac.stanford.edu

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Received on Thu Jun 24 2010 - 23:21:27 CEST

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