Hello—
Sorry, I said I was going to get to this either in the hotel at or on the plane returning from the AGU meeting. I attach six plots, one for each of the six detectors, showing the response of each to protons coming in at
each energy and angle. The angle is averaged over all azimuths as if the sensor was cylindrically symmetrical, and there is no obstruction from the spacecraft in the simulation; however, enough of the solid angle is covered by open space in reality that this
should not make all that much difference quantitatively, and none qualitatively. This set of plots, which includes the D5 and D6 plots I sent during the discussion about possible neutron or gamma response some months ago, is based on the response simulations
that I did in 2010 using Geant4 version 9.3; the single-detector proton response is not likely to change much when I redo them with version 10.5 (that is mainly aimed at understanding shrapnel and “scruff” in multi-detector coincidences).
The colorscale is the logarithm of the effective area of that detector’s singles rate (with flight thresholds applied) for protons arriving at the given energy (X axis) from the given angle off the D6 normal (Y
axis), with the white color denoting the full nominal area (9.6 cm^2) of each detector. You can see that D3 and D4 have some off-axis leakage down to 50 MeV or so, and that D4 in particular has a small sneak path down to about 20 MeV. Let me know if you
need this integrated over angle as a curve vs. energy or something.
Happy new year—
--Mark Looper
Mark D. Looper
Space Sciences Department
The Aerospace Corporation
M/S M2-260
P.O. Box 92957
Los Angeles, CA 90009-2957
Mobile: 310-529-3406
Voicemail: 310-336-6302
From: Anthony Case <tonycase@cfa.harvard.edu>
Date: Thursday, December 6, 2018 at 11:12 AM
To: Mark D Looper <mark.d.looper@aero.org>
Cc: Harlan <spence@guero.sr.unh.edu>, "crater-team@lists.sr.unh.edu" <crater-team@lists.sr.unh.edu>
Subject: Re: [Crater-team] CRaTER Side Shielding
Mark,
In comparing with GOES, we were curious about he response to >50 MeV protons, since GOES has a data product that is integral flux above 50 MeV. Specifically, we were wondering if 50 MeV protons could make it through the side of the instrument
into D3/D4. In looking at the mechanical design, it seemed like there were some paths where protons with energies less than 50 MeV (maybe even down to 30 MeV) could make it through to the detector. Do you have model runs that would answer that question?
Tony
---------------------------------------------------------------------
Anthony Case
Astrophysicist
High Energy Astrophysics Division (HEAD/SSXG)
Center for Astrophysics | Harvard & Smithsonian
Cell: (617) 304 0768
60 Garden Street | MS 58 | Cambridge, MA 02138
On Thu, Dec 6, 2018 at 4:02 PM Mark D Looper <mark.d.looper@aero.org> wrote: